Journal articles on the topic 'Bootstrap adjustment'
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Rocke, David M. "Bootstrap Bartlett Adjustment in Seemingly Unrelated Regression." Journal of the American Statistical Association 84, no. 406 (June 1989): 598–601. http://dx.doi.org/10.1080/01621459.1989.10478809.
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Embrechts, Paul, and Thomas Mikosch. "A bootstrap procedure for estimating the adjustment coefficient." Insurance: Mathematics and Economics 10, no. 3 (December 1991): 181–90. http://dx.doi.org/10.1016/0167-6687(91)90048-3.
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Trenkler, Carsten. "BOOTSTRAPPING SYSTEMS COINTEGRATION TESTS WITH A PRIOR ADJUSTMENT FOR DETERMINISTIC TERMS." Econometric Theory 25, no. 1 (February 2009): 243–69. http://dx.doi.org/10.1017/s0266466608090087.
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In this paper we analyze bootstrap procedures for systems cointegration tests with a prior adjustment for deterministic terms suggested by Saikkonen et al. (2006, Econometric Theory 22, 15–68) and Saikkonen and Lütkepohl (2000, Journal of Time Series Analysis 21, 435–456). The asymptotic properties of the bootstrap test procedures are derived, and their small-sample properties are studied. The simulation study also considers the standard asymptotic test versions and the Johansen cointegration test for comparison.
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Acquah, Henry de-Graft. "A Bootstrap Approach to Evaluating the Power of the Houck’s Test for Asymmetry." Journal of Social and Development Sciences 4, no. 2 (February 28, 2013): 69–73. http://dx.doi.org/10.22610/jsds.v4i2.737.
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The power of the conventional Houck’s model of asymmetry is examined via parametric bootstrap simulation. The results of the bootstrap simulations indicate that the Houck’s model has low power in rejecting the null of symmetric adjustment. The power of the test depends on the bootstrap sample size, level of asymmetry and the amount of noise in the data generating process used in an application. With a small bootstrap sample and large noise level, the Houck’s model display low power in rejecting the null hypothesis of symmetry.
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Acquah, Henry De-Graft. "Using Bootstrap Method to Evaluate the Power of Tests for Non-Linearity in Asymmetric Price Relationship." Journal of Economics and Behavioral Studies 5, no. 4 (April 30, 2013): 237–41. http://dx.doi.org/10.22610/jebs.v5i4.399.
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This paper introduces and applies the bootstrap method to compare the power of the test for asymmetry in the Granger and Lee (1989) and Von Cramon-Taubadel and Loy (1996) models. The results of the bootstrap simulations indicate that the power of the test for asymmetry depends on various conditions such as the bootstrap sample size, model complexity, difference in adjustment speeds and the amount of noise in the data generating process used in the application. The true model achieves greater power when compared with the complex model. With small bootstrap sample size or large noise, both models display low power in rejecting the (false) null hypothesis of symmetry.
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Acquah, Henry de-Graft. "A Comparison of Bootstrap and Monte Carlo Approaches to Testing for Symmetry in the Granger and Lee Error Correction Model." Information Management and Business Review 5, no. 5 (May 30, 2013): 240–44. http://dx.doi.org/10.22610/imbr.v5i5.1048.
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In this paper, I investigate the power of the Granger and Lee model of asymmetry via bootstrap and Monte Carlo techniques. The simulation results indicate that sample size, level of asymmetry and the amount of noise in the data generating process are important determinants of the power of the test for asymmetry based on bootstrap and Monte Carlo techniques. Additionally, the simulation results suggest that both bootstrap and Monte Carlo methods are successful in rejecting the false null hypothesis of symmetric adjustment in large samples with small error size and strong levels of asymmetry. In large samples, with small error size and strong levels of asymmetry, the results suggest that asymmetry test based on Monte Carlo methods achieve greater power gains when compared with the test for asymmetry based on bootstrap. However, in small samples, with large error size and subtle levels of asymmetry, the results suggest that asymmetry test based on bootstrap is more powerful than those based on the Monte Carlo methods. I conclude that both bootstrap and Monte Carlo algorithms provide valuable tools for investigating the power of the test of asymmetry.
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Pitts, Susan M., Rudolf Grübel, and Paul Embrechts. "Confidence bounds for the adjustment coefficient." Advances in Applied Probability 28, no. 3 (September 1996): 802–27. http://dx.doi.org/10.2307/1428182.
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Let ?(u) be the probability of eventual ruin in the classical Sparre Andersen model of risk theory if the initial risk reserve is u. For a large class of such models ?(u) behaves asymptotically like a multiple of exp (–Ru) where R is the adjustment coefficient; R depends on the premium income rate, the claim size distribution and the distribution of the time between claim arrivals. Estimation of R has been considered by many authors. In the present paper we deal with confidence bounds for R. A variety of methods is used, including jackknife estimation of asymptotic variances and the bootstrap. We show that, under certain assumptions, these procedures result in interval estimates that have asymptotically the correct coverage probabilities. We also give the results of a simulation study that compares the different techniques in some particular cases.
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Pitts, Susan M., Rudolf Grübel, and Paul Embrechts. "Confidence bounds for the adjustment coefficient." Advances in Applied Probability 28, no. 03 (September 1996): 802–27. http://dx.doi.org/10.1017/s0001867800046504.
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Let ?(u) be the probability of eventual ruin in the classical Sparre Andersen model of risk theory if the initial risk reserve is u. For a large class of such models ?(u) behaves asymptotically like a multiple of exp (–Ru) where R is the adjustment coefficient; R depends on the premium income rate, the claim size distribution and the distribution of the time between claim arrivals. Estimation of R has been considered by many authors. In the present paper we deal with confidence bounds for R. A variety of methods is used, including jackknife estimation of asymptotic variances and the bootstrap. We show that, under certain assumptions, these procedures result in interval estimates that have asymptotically the correct coverage probabilities. We also give the results of a simulation study that compares the different techniques in some particular cases.
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Kayal, Parthajit, and S. Maheswaran. "Speed of Price Adjustment towards Market Efficiency: Evidence from Emerging Countries." Journal of Emerging Market Finance 17, no. 1_suppl (February 26, 2018): S112—S135. http://dx.doi.org/10.1177/0972652717751542.
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The speed with which stock markets adjust to information and news flow into asset prices is of importance to investors, regulators and policymakers. In this article, we provide a simple and uniform empirical framework involving the use of a volatility measure to compare the speeds of adjustment in index prices in response to all available market information. The stock indices of 23 major emerging economies are compared with 10 mature stock indices from developed countries with reference to the speed of their price adjustments. We find that the index prices of developed countries adjust faster when compared to those of emerging countries. Our findings are independent of any GARCH specification and are also robust to potential mistakes in the model specification because we make use of a fully empirical bootstrap procedure to compute the standard errors. We also rank the countries in terms of the speed of index price adjustment. The results show that the random walk effect is generic and exists in all price indices.
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Chen, Ze Wei, Jun Chai, and Jian Yu Ge. "The Efficacy of CPPI and VBPI Based on Stationary Bootstrap Method." Applied Mechanics and Materials 687-691 (November 2014): 4848–52. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.4848.
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This paper presented an overview of the Stationary Bootstrap method of nonparametric methods. Multitudes of re-sampled data were generated to conquer the limitations of historical simulation method.The trends of different indexes based on Stationary Bootstrap Method were constructed to test the performance of VBPI strategy under different market conditions and compare its performance with CPPI strategy.Test of the significant difference of performance between CPPI and VBPI disclosed that with sufficient samples, confidence level of 99%, insured ratio of 99% or 98% and window period equivalent to adjustment duration at 20 days, VBPI strategy outperformed CPPI strategy in various test indicators.
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ALABA, OLUWAYEMISI OYERONKE, and Afeez Abolaji Lawal. "Bootstrap Bartlett Adjustment on Decomposed Variance-Covariance Matrix of Seemingly Unrelated Regression Model." Afrika Statistika 14, no. 1 (January 1, 2019): 1891–902. http://dx.doi.org/10.16929/as/2019.1891.140.
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Marques, André M. "Testing for asymmetric adjustment in weekly Brazilian inflation." Nova Economia 31, no. 1 (January 2021): 67–85. http://dx.doi.org/10.1590/0103-6351/5269.
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Abstract This study analyses the nature of weekly inflation response to shocks in the Brazilian economy by adopting a generalized quantile autoregression model in which the autoregressive parameter is allowed to be quantile-dependent. We test for unit root at different conditional quantiles of the response variable, by characterizing its asymmetric dynamics along the business cycle. The method allows us to estimate the magnitude, sign, and the significance of actual shocks that affect Brazilian inflation. We evaluate the robustness of results by adopting a bootstrap procedure. Concerning previous studies, we find evidence of stronger asymmetric persistence in inflationary dynamics in which an inflationary shock below the average dissipates very fast when compared to an inflationary impulse occurring above the average. Location, size, and the sign of a random shock might be essential for inflation adjustment towards long-run equilibrium. The results do not support the full inertia hypothesis.
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Lim, So Jung, and Inkyung Jung. "Bootstrap estimation of the standard error of treatment effect with double propensity score adjustment." Korean Journal of Applied Statistics 30, no. 3 (June 30, 2017): 453–62. http://dx.doi.org/10.5351/kjas.2017.30.3.453.
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Ukyo, Yoshifumi, Hisashi Noma, Kazushi Maruo, and Masahiko Gosho. "Improved Small Sample Inference Methods for a Mixed-Effects Model for Repeated Measures Approach in Incomplete Longitudinal Data Analysis." Stats 2, no. 2 (March 28, 2019): 174–88. http://dx.doi.org/10.3390/stats2020013.
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The mixed-effects model for repeated measures (MMRM) approach has been widely applied for longitudinal clinical trials. Many of the standard inference methods of MMRM could possibly lead to the inflation of type I error rates for the tests of treatment effect, when the longitudinal dataset is small and involves missing measurements. We propose two improved inference methods for the MMRM analyses, (1) the Bartlett correction with the adjustment term approximated by bootstrap, and (2) the Monte Carlo test using an estimated null distribution by bootstrap. These methods can be implemented regardless of model complexity and missing patterns via a unified computational framework. Through simulation studies, the proposed methods maintain the type I error rate properly, even for small and incomplete longitudinal clinical trial settings. Applications to a postnatal depression clinical trial are also presented.
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Schild, Karl-Heinz, and Karsten Schweikert. "On the Validity of Tests for Asymmetry in Residual-Based Threshold Cointegration Models." Econometrics 7, no. 1 (March 13, 2019): 12. http://dx.doi.org/10.3390/econometrics7010012.
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This paper investigates the properties of tests for asymmetric long-run adjustment which are often applied in empirical studies on asymmetric price transmissions. We show that substantial size distortions are caused by preconditioning the test on finding sufficient evidence for cointegration in a first step. The extent of oversizing the test for long-run asymmetry depends inversely on the power of the primary cointegration test. Hence, tests for long-run asymmetry become invalid in cases of small sample sizes or slow speed of adjustment. Further, we provide simulation evidence that tests for long-run asymmetry are generally oversized if the threshold parameter is estimated by conditional least squares and show that bootstrap techniques can be used to obtain the correct size.
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Perel, Sagi, Andrew B. Schwartz, and Valérie Ventura. "Single-Snippet Analysis for Detection of Postspike Effects." Neural Computation 26, no. 1 (January 2014): 40–56. http://dx.doi.org/10.1162/neco_a_00531.
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Corticomotoneuronal cells (CMN), located predominantly in the primary motor cortex, project directly to alpha motoneuronal pools in the spinal cord. The effects of CMN spikes on motoneuronal excitability are traditionally characterized by visualizing postspike effects (PSEs) in spike-triggered averages (SpTA; Fetz, Cheney, & German, 1976 ; Fetz & Cheney, 1980 ; McKiernan, Marcario, Karrer, & Cheney, 1998 ) of electromyography (EMG) data. Poliakov and Schieber ( 1998 ) suggested a formal test, the multiple-fragment analysis (MFA), to automatically detect PSEs. However, MFA's performance was not statistically validated, and it is unclear under what conditions it is valid. This paper's contributions are a power study that validates the MFA; an alternative test, the single-snippet analysis (SSA), which has the same functionality as MFA but is easier to calculate and has better power in small samples; a simple bootstrap simulation to estimate SpTA baselines with simulation bands that help visualize potential PSEs; and a bootstrap adjustment to the MFA and SSA to correct for nonlinear SpTA baselines.
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Debón, Ana, Steven Haberman, Francisco Montes, and Edoardo Otranto. "Do Different Models Induce Changes in Mortality Indicators? That Is a Key Question for Extending the Lee-Carter Model." International Journal of Environmental Research and Public Health 18, no. 4 (February 23, 2021): 2204. http://dx.doi.org/10.3390/ijerph18042204.
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The parametric model introduced by Lee and Carter in 1992 for modeling mortality rates in the USA was a seminal development in forecasting life expectancies and has been widely used since then. Different extensions of this model, using different hypotheses about the data, constraints on the parameters, and appropriate methods have led to improvements in the model’s fit to historical data and the model’s forecasting of the future. This paper’s main objective is to evaluate if differences between models are reflected in different mortality indicators’ forecasts. To this end, nine sets of indicator predictions were generated by crossing three models and three block-bootstrap samples with each of size fifty. Later the predicted mortality indicators were compared using functional ANOVA. Models and block bootstrap procedures are applied to Spanish mortality data. Results show model, block-bootstrap, and interaction effects for all mortality indicators. Although it was not our main objective, it is essential to point out that the sample effect should not be present since they must be realizations of the same population, and therefore the procedure should lead to samples that do not influence the results. Regarding significant model effect, it follows that, although the addition of terms improves the adjustment of probabilities and translates into an effect on mortality indicators, the model’s predictions must be checked in terms of their probabilities and the mortality indicators of interest.
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Li, Xin, Hsu Ling Chang, Chi Wei Su, and Yin Dai. "Does foreign direct investment promote exports in China?" China Finance Review International 7, no. 2 (May 15, 2017): 185–202. http://dx.doi.org/10.1108/cfri-04-2016-0026.
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Purpose The purpose of this paper is to investigate the causal link between foreign direct investment (FDI) and exports in China based on the knowledge capital model (KK model, Markusen, 2002). Design/methodology/approach The bootstrap Granger full-sample and sub-sample rolling window causality test is used to determine whether FDI can promote exports. Findings The full-sample causality test indicates no causal relationship from FDI to exports. However, considering structural changes of exports and FDI, the authors’ find that the full-sample test is not reliable. Instead, the authors use the rolling window causality test to revisit the dynamic causal relationship, and the results present significant effects from FDI on exports, mostly around periods in which the proportion of FDI from Hong Kong, Macao and Taiwan is increasing. Specifically, positive impacts of FDI on exports are stronger than the negative impacts in China. Research limitations/implications The findings in this study suggest a significant time-varying nature of the correlation between FDI and exports. The promotion effect of FDI to exports is proved by the rolling window approach; it thus supports the KK model that divides FDI into lateral FDI and vertical FDI and proves that the constitution of FDI is critical to the relationship between FDI and exports. Practical implications China has been facing adjustment of its economic structure in recent years, and in this situation, increasing the proportion of FDI that can bring advanced production function is critical for the industrial structural adjustment. Originality/value This paper uses the bootstrap rolling window causality test to investigate the time-varying nature of the causality between FDI and exports, considering structural changes for the first time. The authors further deepen the previous research and draw a more realistic conclusion.
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Ryan, P., J. E. Hiller, and G. Mnatzaganian. "Does Co-morbidity Provide Significant Improvement on Age Adjustment when Predicting Medical Outcomes?" Methods of Information in Medicine 53, no. 02 (2014): 115–20. http://dx.doi.org/10.3414/me13-01-0095.
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SummaryObjective: Using three risk-adjustment methods we evaluated whether co-morbidity derived from electronic hospital patient data provided significant improvement on age adjustment when predicting major outcomes following an elective total joint replacement (TJR) due to osteoarthritis.Methods: Longitudinal data from 819 elderly men who had had a TJR were integrated with hospital morbidity data (HMD) and mortality records. For each participant, any mor bidity or health-related outcome was retrieved from the linked data in the period 1970 through to 2007 and this enabled us to better account for patient co-morbidities. Co-mor bidities recorded in the HMD in all admissions preceding the index TJR admission were used to construct three risk-adjustment methods, namely Charlson co-morbidity index (CCI), Elixhauser’s adjustment method, and number of co-morbidities. Postoperative outcomes evaluated included length of hospital stay, 90-day readmission, and 1-year and 2-year mortality. These were modelled using Cox proportional hazards regression as a function of age for the baseline models, and as a function of age and each of the risk-adjustment methods. The difference in the statistical performance between the models that included age alone and those that also included the co-morbidity adjustment method was as sessed by measuring the difference in the Harrell’s C estimates between pairs of mod els applied to the same patient data using Bootstrap analysis with 1000 replications.Results: Number of co-morbidities did not provide any significant improvement in model discrimination when added to baseline models observed in all outcomes. CCI significantly improved model discrimination when predicting post-operative mortality but not when length of stay or readmission was modelled. For every one point increase in CCI, postoperative 1- and 2-year mortality increased by 37% and 30%, respectively. Elixhauser’s method outperformed the other two providing significant improvement on age adjustment in all outcomes.Conclusion: The predictive performance of co-morbidity derived from electronic hospital data is outcome and risk-adjustment method specific.
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Khikmah, Khusnia Nurul. "FUNCTIONAL PREDICTION REGRESSION VIA BOOSTING UNTUK PEMODELAN CURAH HUJAN DI PROVINSI JAWA TIMUR." MATHunesa: Jurnal Ilmiah Matematika 9, no. 2 (August 31, 2021): 242–50. http://dx.doi.org/10.26740/mathunesa.v9n2.p242-250.
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Natural phenomena that can cause natural changes on earth caused by increasing greenhouse gases and decreasing landthat absorbs carbon dioxide are called climate change. The elements that cause changes include rainfall and temperature.The constantly rising temperature of the earth results in changing rainfall patterns and can have various effects on theenvironment. Therefore, research on rainfall modeling with annual average temperature and rainfall data from theprovince of East Java from 2006 to 2017 which was taken from the official website of the Central Statistics Agency ofEast Java Province makes sense. This data is a data multivariate time series that is approached with Functional DataAnalysis and modeled using Functional Prediction Regression. Functional Prediction Regression is a form of modelingwith functional data that can test the overall model for high-dimensional data and one of the improved methods ofregression methods for functional data. One way to model Functional Prediction Regression is through boosting. Thisresearch conducted rainfall modeling with Functional Prediction Regression through boosting from East Java Provinceand obtained modeling results using an additional predictor model with 5-fold bootstrap and adjustment of the splineregression (knots) used, namely 16 indicated by the iteration value-boosting bootstrap where the model used to have alinear functional effect of 𝑚𝑠𝑡𝑜𝑝 for the mu parameter and 100 for the sigma parameter.
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Parker, Thomas. "A COMPARISON OF ALTERNATIVE APPROACHES TO SUPREMUM-NORM GOODNESS-OF-FIT TESTS WITH ESTIMATED PARAMETERS." Econometric Theory 29, no. 5 (February 21, 2013): 969–1008. http://dx.doi.org/10.1017/s0266466612000825.
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Goodness-of-fit tests based on parametric empirical processes have nonstandard limiting distributions when the null hypothesis is composite — that is, when parameters of the null model are estimated. Several analytic solutions to this problem have been suggested, including the calculation of adjusted critical values for these nonstandard distributions and the transformation of the empirical process such that statistics based on the transformed process are asymptotically distribution-free. The approximation methods proposed by Durbin (1985, Journal of Applied Probability 22(1), 99–122) can be applied to conduct inference for tests based on supremum-norm statistics. The resulting tests have quite accurate size, a fact that has gone unrecognized in the econometrics literature. Some justification for this accuracy lies in the similar features that Durbin’s approximation methods share with the theory of extrema for Gaussian random fields and for Gauss-Markov processes. These adjustment techniques are also related to the transformation methodology proposed by Khmaladze (1981, Theory of Probability and Its Applications26(2), 240–257) through the score function of the parametric model. Simulation experiments suggest that in small samples, Durbin-style adjustments result in tests that have higher power than tests based on transformed processes, and in some cases they have higher power than parametric bootstrap procedures.
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Jatuworapruk, Kanon, Rebecca Grainger, Nicola Dalbeth, and William J. Taylor. "Development of a prediction model for inpatient gout flares in people with comorbid gout." Annals of the Rheumatic Diseases 79, no. 3 (December 6, 2019): 418–23. http://dx.doi.org/10.1136/annrheumdis-2019-216277.
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ObjectivesHospitalisation is a risk factor for flares in people with gout. However, the predictors of inpatient gout flare are not well understood. The aim of this study was to develop a prediction model for inpatient gout flare among people with comorbid gout.MethodsWe used data from a retrospective cohort of hospitalised patients with comorbid gout from Wellington, Aotearoa/New Zealand, in 2017 calendar year. For the development of a prediction model, we took three approaches: (A) a clinical knowledge-driven model, (B) a statistics-driven model and (C) a decision tree model. The final model was chosen based on practicality and performance, then validated using bootstrap procedure.ResultsThe cohort consisted of 625 hospitalised patients with comorbid gout, 87 of whom experienced inpatient gout flare. Model A yielded 9 predictors of inpatient gout flare, while model B and C produced 15 and 5, respectively. Model A was chosen for its simplicity and superior C-statistics (0.82) and calibration slope (0.93). The final nine-item set of predictors were pre-admission urate >0.36 mmol/L, tophus, no pre-admission urate-lowering therapy (ULT), no pre-admission gout prophylaxis, acute kidney injury, surgery, initiation or increase of gout prophylaxis, adjustment of ULT and diuretics prior to flare. Bootstrap validation of the final model showed adequate C-statistics and calibration slope (0.80 and 0.78, respectively).ConclusionWe propose a set of nine predictors of inpatient flare for people with comorbid gout. The predictors are simple, practical and are supported by existing clinical knowledge.
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Setiawan, Maman, and Alfons G. J. M. Oude Lansink. "Dynamic technical inefficiency and industrial concentration in the Indonesian food and beverages industry." British Food Journal 120, no. 1 (January 2, 2018): 108–19. http://dx.doi.org/10.1108/bfj-04-2017-0226.
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Purpose The purpose of this paper is to investigate the relation between industrial concentration and technical inefficiency in the Indonesian food and beverages industry using a dynamic performance measure (dynamic technical inefficiency) that accounts for the presence of adjustment costs. Design/methodology/approach This research uses panel data of 44 subsectors in the Indonesian food and beverages industry for the period 1980-2014. The dynamic input directional distance function is applied to estimate the dynamic technical inefficiency. Further, the Granger causality between industrial concentration and dynamic technical inefficiency is tested using a dynamic panel data model. A bootstrap truncated regression model is finally applied to estimate the relation between industrial concentration and dynamic technical inefficiency based on the results from the Granger causality test. Findings The results show that the Indonesian food and beverages industry has a high dynamic technical inefficiency. Investigation of the causality of the relation shows that industrial concentration has a positive effect on dynamic technical inefficiency at the subsector level, with no reversed causality. The results suggest that the quiet life hypothesis applies to the Indonesian food and beverages industry. Originality/value The literature investigating the relation between industrial concentration and performance relies on static measures of performance, such as technical efficiency. Static measures provide an incorrect metric of the firms’ performance in the presence of adjustment costs associated with investment. Therefore, this research has a contribution in measuring dynamic technical inefficiency that accounts for the presence of the adjustment cost as well as its relation with industrial concentration in the Indonesian food and beverages industry.
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Ventura, Valérie, Can Cai, and Robert E. Kass. "Trial-to-Trial Variability and Its Effect on Time-Varying Dependency Between Two Neurons." Journal of Neurophysiology 94, no. 4 (October 2005): 2928–39. http://dx.doi.org/10.1152/jn.00644.2004.
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The joint peristimulus time histogram (JPSTH) and cross-correlogram provide a visual representation of correlated activity for a pair of neurons, and the way this activity may increase or decrease over time. In a companion paper we showed how a Bootstrap evaluation of the peaks in the smoothed diagonals of the JPSTH may be used to establish the likely validity of apparent time-varying correlation. As noted in earlier studies by Brody and Ben-Shaul et al., trial-to-trial variation can confound correlation and synchrony effects. In this paper we elaborate on that observation, and present a method of estimating the time-dependent trial-to-trial variation in spike trains that may exceed the natural variation displayed by Poisson and non-Poisson point processes. The statistical problem is somewhat subtle because relatively few spikes per trial are available for estimating a firing-rate function that fluctuates over time. The method developed here decomposes the spike-train variability into a stimulus-related component and a trial-specific component, allowing many degrees of freedom to characterize the former while assuming a small number suffices to characterize the latter. The Bootstrap significance test of the companion paper is then modified to accommodate these general excitability effects. This methodology allows an investigator to assess whether excitability effects are constant or time-varying, and whether they are shared by two neurons. In data from two V1 neurons we find that highly statistically significant evidence of dependency disappears after adjustment for time-varying trial-to-trial variation.
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Qu, Yunlong, Guiling Sun, Bowen Zheng, and Wang Liu. "Environment Monitoring System of Dairy Cattle Farming Based on Multi Parameter Fusion." Information 12, no. 7 (July 1, 2021): 273. http://dx.doi.org/10.3390/info12070273.
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Aiming at the difficulty in obtaining environmental parameters in dairy cattle breeding, this paper proposes and implements a dairy cattle breeding environment monitoring system based on Bluetooth and B/S architecture. In order to reduce the cost of cross-platform deployment, the overall system adopts the B/S architecture and introduces a Bootstrap responsive layout; in order to improve the human–computer interaction capabilities, the Echarts graphical plug-in is introduced; and in order to enhance the stability of Bluetooth communication, a time-sharing connection mechanism and sampling are designed along with a cycle adaptive adjustment mechanism. The experimental results show that the system has a good user experience on various smart terminal devices. The time-sharing connection mechanism solves the repeated disconnection problem under the Bluetooth one-master, multiple-slave star connection. The system can be used in the dairy cow growth environment. With real-time monitoring and accurate early warning, it reduces the deployment and use cost of the system and has broad application prospects.
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Shittu, Umar, Idris Zainab-L, Umma Sada, and Bashir Aliyu. "Epidemiological Distinctive Survey Of Children With Acute Respiratory Tract Infections In Some Selected Hospitals Of Katsina Metropolis, Nigeria." Journal of Basic and Applied Research in Biomedicine 6, no. 2 (December 23, 2020): 120–23. http://dx.doi.org/10.51152/jbarbiomed.v6i2.126.
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Acute respiratory tract infections (ARIs) in children under the age group of five (5) years are serious infections, which prevent the normal breathing function in the child's system. The infection usually begins as a viral infection in which it enters the child's system through the nose to the trachea (windpipe) and down to the lungs. This study aimed to identify the distinctive risk factors associated with the respiratory tract infection in which later it can lead the infection to become acute and find out the easy ways toward preventing the infections. The study was performed within the period of six (6) months during the rainy season between the periods of April to September using the human subjects under age group of five (5) years. The data analysis was done in the Bioconductor R package, statistics p-value with associated B-value were obtained from the distribution of the moderated t-statistic after the adjustment for multiple testing with a significance level of ((? 0.05) using LIMMA method. Pvclust method was also used to generate thousands of bootstrap samples by randomly sampling elements of the data and then compute graphic hierarchical clustering on each bootstrap copy. Distinctive risk factors of (ARTI) were identified, such as malnutrition (MNT), indoor air pollution (IAP), Crowdy and dirty environment (CDE), and parental education (PE) which shows significant influence on the infection. But indoor air pollution (IAP) with the highest level of significant influence to the infections. It is recommended that parents having children should be enlightened by the health personnel experts through different media communication channels and other channels in order to avoid leaving in dirty, crowdy and unventilated environment and to feed from recommended diets with their children.
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Boykin, Derrecka M., Qweandria T. Dunn, and Holly K. Orcutt. "Cumulative Trauma and Adjustment in Women Exposed to a Campus Shooting: Examining the Role of Appraisals and Social Support." Journal of Interpersonal Violence 35, no. 17-18 (May 29, 2017): 3601–21. http://dx.doi.org/10.1177/0886260517710483.
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Experiencing repeated trauma can have increasingly detrimental effects on psychosocial functioning after subsequent stressors. These effects may be intensified for victims of interpersonal traumas given that these events are often associated with heightened risk for adverse outcomes. To better understand this relationship, the present study prospectively examined the effect of pre-shooting trauma exposure (i.e., interpersonal vs. non-interpersonal trauma) on psychological functioning (i.e., posttraumatic stress symptoms, depression) following a mass campus shooting. Based on previous research, it was expected that negative appraisals and social support would mediate this relationship. A sample of 515 college women reporting prior trauma exposure was assessed at four time points following the shooting (i.e., pre-shooting, 1-month, 6-months, and 12-months post-shooting). Bootstrap analyses with bias-corrected confidence intervals were conducted. Contrary to expectation, pre-shooting trauma exposure was unrelated to 12-month post-shooting outcomes and neither negative appraisals nor social support at 6-months post-shooting emerged as mediators. Interestingly, a history of non-interpersonal trauma was associated with greater post-shooting family and friend support than a history of interpersonal trauma. Ad hoc analyses showed that pre-shooting symptom severity and level of exposure to the shooting had indirect effects on post-shooting outcomes via post-shooting negative appraisals. These findings support that cumulative trauma, regardless of type, may not have an additive effect unless individuals develop clinically significant symptoms following previous trauma. Trauma severity also appears to play a meaningful role.
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Lee, Beatrice, Cahit Kaya, Xiangli Chen, Jia-Rung Wu, Kanako Iwanaga, Emre Umucu, Jill Bezyak, Timothy N. Tansey, and Fong Chan. "The Buffering Effect of Character Strengths on Depression." European Journal of Health Psychology 26, no. 3 (July 2019): 101–9. http://dx.doi.org/10.1027/2512-8442/a000036.
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Abstract. The transition from high school to college can be very stressful for Turkish students because they may experience value conflicts and adjustment issues, which can trigger the development of mental health problems. Character strengths can serve as a buffer against psychopathology. The aim of the study was to examine perceived stress and negative attributional style as mediating factors between character strengths and depression among Turkish college students. Bootstrap testing approach was implemented to compute direct and indirect effects and total effect in the mediation analysis. Altogether 235 students from two Turkish universities participated in the study. The results showed that character strengths were associated with lower levels of depression and it was negatively associated with perceived stress and negative attributional style. The results also indicated that perceived stress and negative attribution style completely mediated the relationship between character strengths and depression among Turkish college students. These findings suggested the need to develop empirically supported interventions that can promote character strengths toward reducing stress, negative attributions, and depression in this population.
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Power, James H., and E. Barry Moser. "Linear model analysis of net catch data using the negative binomial distribution." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 2 (February 1, 1999): 191–200. http://dx.doi.org/10.1139/f98-150.
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Sampling with nets or trawls remains a common technique for determining the comparative abundances of aquatic organisms, and the objective of such studies is frequently to evaluate relationships among the counts of individuals caught and exogenous variables. Analysis of such data is often done with a general linear model (e.g., ANOVA, ANCOVA, regression), assuming an underlying normal probability distribution. Such analyses are not fully satisfactory because of the symmetry and continuous nature of the assumed normal probability distribution and the high variance to low mean value relationships common to counts of biological populations. The negative binomial is a discrete probability distribution that is recognized as a suitable descriptor of organism count data. We present an approach for undertaking linear model analyses of net catch data that permits estimation of model parameters (including the negative binomial k parameter) and hypothesis testing of both continuous and discrete model effects and their interactions using bootstrap replication. The analysis incorporates adjustment for varying element sizes, such as differences in the amounts of water filtered during sampling.
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Gefeller, O., T. Rabenstein, T. Hothorn, and M. Radespiel-Tröger. "Association between Split Selection Instability and Predictive Error in Survival Trees." Methods of Information in Medicine 45, no. 05 (2006): 548–56. http://dx.doi.org/10.1055/s-0038-1634117.
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Summary Objectives: To evaluate split selection instability in six survival tree algorithms and its relationship with predictive error by means of a bootstrap study. Methods: We study the following algorithms: logrank statistic with multivariate p-value adjustment without pruning (LR), Kaplan-Meier distance of survival curves (KM), martingale residuals (MR), Poisson regression for censored data (PR), within-node impurity (WI), and exponential log-likelihood loss (XL). With the exception of LR, initial trees are pruned by using split-complexity, and final trees are selected by means of cross-validation. We employ a real dataset from a clinical study of patients with gallbladder stones. The predictive error is evaluated using the integrated Brier score for censored data. The relationship between split selection instability and predictive error is evaluated by means of box-percentile plots, covariate and cutpoint selection entropy, and cutpoint selection coefficients of variation, respectively, in the root node. Results: We found a positive association between covariate selection instability and predictive error in the root node. LR yields the lowest predictive error, while KM and MR yield the highest predictive error. Conclusions: The predictive error of survival trees is related to split selection instability. Based on the low predictive error of LR, we recommend the use of this algorithm for the construction of survival trees. Unpruned survival trees with multivariate p-value adjustment can perform equally well compared to pruned trees. The analysis of split selection instability can be used to communicate the results of tree-based analyses to clinicians and to support the application of survival trees.
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Venekamp, Roderick, Jens Georg Hansen, Johannes B. Reitsma, Mark H. Ebell, and Morten Lindbaek. "Accuracy of signs, symptoms and blood tests for diagnosing acute bacterial rhinosinusitis and CT-confirmed acute rhinosinusitis in adults: protocol of an individual patient data meta-analysis." BMJ Open 10, no. 11 (November 2020): e040988. http://dx.doi.org/10.1136/bmjopen-2020-040988.
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IntroductionThis protocol outlines a diagnostic individual patient data (IPD) meta-analysis aimed at developing simple prediction models based on readily available signs, symptoms and blood tests to accurately predict acute bacterial rhinosinusitis and CT-confirmed (fluid level or total opacification in any sinus) acute rhinosinusitis (ARS) in adults presenting to primary care with clinically diagnosed ARS, target conditions associated with antibiotic benefit.Methods and analysisThe systematic searches of PubMed and Embase of a review on the accuracy of signs and symptoms for diagnosing ARS in ambulatory care will be updated to April 2020 to identify relevant studies. Authors of eligible studies will be contacted and invited to provide IPD. Methodological quality of the studies will be assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Candidate predictor selection will be based on knowledge from existing literature, clinical reasoning and availability. Multivariable logistic regression analyses will be used to develop prediction models aimed at calculating absolute risk estimates. Large unexplained between-study heterogeneity in predictive accuracy of the models will be explored and may lead to either model adjustment or derivation of separate context-specific models. Calibration and discrimination will be evaluated to assess the models’ performance. Bootstrap resampling techniques will be used to assess internal validation and to inform on possible adjustment for overfitting. In addition, we aim to perform internal–external cross-validation procedures.Ethics and disseminationIn this IPD meta-analysis, no identifiable patient data will be used. As such, the Medical Research Involving Humans Subject Act does not apply, and official ethical approval is not required. Findings will be published in international peer-reviewed journals and presented at scientific conferences.PROSPERO registration numberPROSPERO CRD42020175659.
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Handorf, Elizabeth A., Daniel F. Heitjan, Justin E. Bekelman, and Nandita Mitra. "Estimating cost-effectiveness from claims and registry data with measured and unmeasured confounders." Statistical Methods in Medical Research 28, no. 7 (February 22, 2018): 2227–42. http://dx.doi.org/10.1177/0962280218759137.
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The analysis of observational data to determine the cost-effectiveness of medical treatments is complicated by the need to account for skewness, censoring, and the effects of measured and unmeasured confounders. We quantify cost-effectiveness as the Net Monetary Benefit (NMB), a linear combination of the treatment effects on cost and effectiveness that denominates utility in monetary terms. We propose a parametric estimation approach that describes cost with a Gamma generalized linear model and survival time (the canonical effectiveness variable) with a Weibull accelerated failure time model. To account for correlation between cost and survival, we propose a bootstrap procedure to compute confidence intervals for NMB. To examine sensitivity to unmeasured confounders, we derive simple approximate relationships between naïve parameters, assuming only measured confounders, and the values those parameters would take if there was further adjustment for a single unmeasured confounder with a specified distribution. A simulation study shows that the method returns accurate estimates for treatment effects on cost, survival, and NMB under the assumed model. We apply our method to compare two treatments for Stage II/III bladder cancer, concluding that the NMB is sensitive to hypothesized unmeasured confounders that represent smoking status and personal income.
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KAFATOS, G., N. ANDREWS, K. J. McCONWAY, C. ANASTASSOPOULOU, C. BARBARA, F. DE ORY, K. JOHANSEN, et al. "Estimating seroprevalence of vaccine-preventable infections: is it worth standardizing the serological outcomes to adjust for different assays and laboratories?" Epidemiology and Infection 143, no. 11 (November 25, 2014): 2269–78. http://dx.doi.org/10.1017/s095026881400301x.
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SUMMARYThe aim of the European Sero-Epidemiology Network 2 (ESEN2) project was to estimate age-specific seroprevalence for a number of vaccine-preventable diseases in Europe. To achieve this serosurveys were collected by 22 national laboratories. To adjust for a variety of laboratory methods and assays, all quantitative results were transformed to a reference laboratory's units and were then classified as positive or negative to obtain age-specific seroprevalence. The aim of this study was to assess the value of standardization by comparing the crude and standardized seroprevalence estimates. Seroprevalence was estimated for measles, mumps, rubella, diphtheria, varicella zoster and hepatitis A virus (HAV) and compared before and after serological results had been standardized. The results showed that if no such adjustment had taken place, seroprevalence would have differed by an average of 3·2% (95% bootstrap interval 2·9–3·6) although this percentage varied substantially by antigen. These differences were as high as 16% for some serosurveys (HAV) which means that standardization could have a considerable impact on seroprevalence estimates and should be considered when comparing serosurveys performed in different laboratories using different assay methods.
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Du, Jungang. "An Empirical Study on Relationship between Residents’ Disposable Income and CPI Based on TVECM: Application of Bootstrap SupLM Testing for Threshold Cointegration." Journal of Mathematics 2022 (September 13, 2022): 1–11. http://dx.doi.org/10.1155/2022/1691686.
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Based on the fluctuation characteristics of residents’ disposable income and CPI (Consumer Price Index) in different periods, this article introduces a nonlinear threshold cointegration theory, establishes a TVECM (Threshold Vector Error Correction Model) of the residents’ disposable income and CPI. We propose an algorithm to obtain maximum likelihood estimation under the condition of cointegration vector and threshold value which are unknown and then propose a SupLM test for the presence of a threshold. The asymptotic distribution of the SupLM statistic is analyzed, and it appears to depend on the moment functionals, so tabulated critical values are unavailable. We discuss how the residual bootstrap can be used to calculate asymptotic critical values and p values, investigate the size and power of the SupLM test using Monte Carlo simulation, and find that the test works quite well. In the empirical section, we apply our methods to test and estimate the TVECM of residents’ disposable income and CPI. According to the experimental results, the causal relationship between residents’ disposable income and CPI under different mechanisms is tested and compared with the test results under the linear cointegration hypothesis. The empirical results show that the disposable income of residents and CPI belong to a two-mechanism nonlinear threshold cointegration system. When the deviation from the equilibrium state exceeds the threshold value, the system may adjust to the equilibrium state, and the adjustment speed of CPI shall be faster than that of the residents’ disposable income.
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Watson, Jack D., and Paul B. Perrin. "Relations among Stigma, Quality of Life, Resilience, and Life Satisfaction in Individuals with Burn Injuries." European Burn Journal 3, no. 1 (February 15, 2022): 145–55. http://dx.doi.org/10.3390/ebj3010012.
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This study examined the relations among burn stigma, quality of life, resilience, and life satisfaction, hypothesizing that higher stigma and lower burn-related quality of life would lead to lower life satisfaction; however, resilience would moderate this relation. A sample of 89 participants was recruited from an outpatient clinic of a burn center in a critical care hospital. Participants completed a battery of measures assessing these constructs. Results suggested that burn stigma was associated with reduced life satisfaction after accounting for other variables. Multiple regression models found that burn stigma predicted both affect and body image but not interpersonal relationship quality or sexuality. Interpersonal relationship quality, sexuality, affect, and body image all predicted life satisfaction. Both affect and body image partially accounted for the relation between stigma and life satisfaction, and resilience accounted for the relation between stigma and affect. Findings reinforce previous literature that has shown a relationship between stigma and life satisfaction but also emphasizes the role of resilience and burn-related quality of life. Individuals who experience a burn injury may have innate resilience abilities, which allow them to bounce back from stressors; thus, resilience can be a targeted strength to bootstrap in order to improve adjustment outcomes.
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Lúcio, Alessandro Dal’Col, Maria I. Diel, Francieli L. Tartaglia, Patrícia J. Melo, André L. Tischler, Darlei M. Lambrecht, João A. Zemolin, and Lucas E. Marques. "Production cycle and characterization of Italian zucchini genotypes by the logistic model." Horticultura Brasileira 39, no. 3 (September 21, 2021): 264–71. http://dx.doi.org/10.1590/s0102-0536-20210304.
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ABSTRACT This study aimed to identify the productive cycle response of Italian zucchini genotypes grown under field conditions in two growing seasons using the nonlinear logistic model and its critical points. Two randomized block experiments were conducted, with three genotypes (Caserta, PX13067051, and Tronco) and two growing seasons (spring-summer and summer-fall), with eight replicates and each experimental unit consisting of 7 plants. The logistic nonlinear model was adjusted for the fruit mass variable, as a function of the accumulated thermal sum, and the critical points were estimated by the partial derivatives of the adjusted function. Adjustment by bootstrap resampling was performed to address the violation of assumptions. The results of intrinsic and parametric nonlinearity confirm the quality of the model fit. This experiment demonstrated that the zucchini genotypes evaluated were more productive in the spring-summer growing season, using the parameters and critical points obtained from the logistic nonlinear model. Genotypes PX13067051 and Caserta showed superior productivity to the Tronco genotype, and also fruited earlier and at a higher rate of production. The logistic growth model and its critical points characterized the production cycle of the zucchini genotypes in different growing seasons and allowed inferences to be made to differentiate the genotypes and the growing seasons.
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Winter, Max-Paul, Georg Goliasch, Philipp Bartko, Jolanta Siller-Matula, Mohamed Ayoub, Stefan Aschauer, Klaus Distelmaier, et al. "Left Main Coronary Artery Disease and Outcomes after Percutaneous Coronary Intervention for Chronic Total Occlusions." Journal of Clinical Medicine 9, no. 4 (March 30, 2020): 938. http://dx.doi.org/10.3390/jcm9040938.
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Background: Concomitant left main coronary artery (LMCA) disease in patients with chronic total occlusions (CTO) commonly results in referral for coronary artery bypass grafting, although the impact of LMCA in CTO patients remains largely unknown. Nevertheless, patient selection for percutaneous coronary intervention of CTOs (CTO-PCI) or alternative revascularization strategies should be based on precise evaluation of the coronary anatomy to anticipate those patients that most likely benefit from a procedure and not on strict adherence to perpetual clinical practice. Therefore, the aim of this study was to assess the impact of LMCA disease on long-term outcomes in patients undergoing percutaneous coronary intervention for CTO. Methods: We enrolled 3860 consecutive patients undergoing PCI for at least one CTO lesion and investigated the predictive value of concomitant LMCA disease. All-cause mortality was defined as the primary study endpoint. Results: We observed that LMCA disease is significantly associated with mortality. In the Cox regression analysis, we observed a crude hazard ratio (HR) 1.59 (95% confidence interval (CI) 1.23–2.04, p < 0.001) for patients with LMCA disease as compared to patients without. Results remained unchanged after bootstrap- or clinical confounder-based adjustment. Conclusion: LMCA disease is associated with excess mortality in CTO patients. Specifically, anatomical features such as CTO of the circumflex artery represent a high risk patient population.
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Szcześniak, Małgorzata, and Celina Timoszyk-Tomczak. "Religious Struggle and Life Satisfaction Among Adult Christians: Self-esteem as a Mediator." Journal of Religion and Health 59, no. 6 (September 10, 2020): 2833–56. http://dx.doi.org/10.1007/s10943-020-01082-9.
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AbstractThe religious dimension of life represents an important source of human strength, meaning, and coping for many people. However, the religious life is not always “smooth and easy” and can be associated with weak personal adjustment, poorer psychological well-being, and lower satisfaction. Yet, besides the direct relationship between these variables, some researchers postulate the existence of an indirect association that has not been fully explained by various psychosocial mediators. The aim of the present study was to verify whether self-esteem could be a potential mediator between religious strain and life satisfaction. The sample consisted of 607 adult Christians (49.6% women) aged between 18 and 79. We used the Religious Comfort and Strain Scale, the Satisfaction with Life Scale, and the Rosenberg Self-Esteem Scale. Consistent with our hypotheses, life satisfaction positively correlated with religious comfort and was negatively associated with fear/guilt, negative emotions toward God, and negative social interactions surrounding religion. The same pattern of results was shown in the case of self-esteem. Moreover, the outcomes obtained from bootstrap sampling (5000) with a 95% confidence interval indicated a significant role of self-esteem as a mediator in all of the relationships between: (1) religious comfort and life satisfaction; (2) fear/guilt and life satisfaction; (3) negative emotions toward God and life satisfaction; and (4) negative social interactions surrounding religion and life satisfaction.
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Wilkie, Ross, Simran Singh Parmar, Milica Blagojevic-Bucknall, Diane Smith, Martin J. Thomas, Bethany Jane Seale, Gemma Mansell, and George Peat. "Reasons why osteoarthritis predicts mortality: path analysis within a Cox proportional hazards model." RMD Open 5, no. 2 (November 2019): e001048. http://dx.doi.org/10.1136/rmdopen-2019-001048.
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ObjectivesTo identify potentially modifiable factors that mediate the association between symptomatic osteoarthritis (OA) and premature mortality.MethodsA population-based prospective cohort study; primary care medical record data were linked to self-report information collected by questionnaire in adults aged 50 years and over (n=10 415). OA was defined by primary care consultation and moderate-to-severe pain interference in daily life. A Cox proportional hazards analysis determined the total effect (TE) of OA on mortality after adjustment for potential confounders. Within the Cox model, path analysis was used to decompose the TE to assess the indirect and direct effects for selected potential mediators (anxiety, depression, unrefreshed sleep and walking frequency). Results are expressed as HRs with 95% CIs derived from bootstrap resampling.ResultsOA was significantly associated with mortality (TE-adjusted HR 1.14; 95% CI 1.00 to 1.29). The indirect effects for walking frequency were 1.05 (95% CI 1.04 to 1.06), depression 1.02 (95% CI 1.02 to 1.03), anxiety 1.01 (95% CI 1.00 to 1.02) and unrefreshed sleep 1.01 (95% CI 1.00 to 1.01).ConclusionsThe analysis indicates that encouraging people to walk and ‘get out and about’ in addition to targeting OA could be protective against excessive mortality. The findings also suggest that depression, anxiety and unrefreshed sleep have a role in premature mortality for people with OA; however, this has low clinical significance.
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Maxim, Adrian. "Notice of Violation of IEEE Publication Principles A 54 dBOmega + 42 dB 10 Gb/s SiGe transimpedance-limiting amplifier using bootstrap photodiode capacitance neutralization and vertical threshold adjustment." IEEE Journal of Solid-State Circuits 42, no. 9 (September 2007): 1851–64. http://dx.doi.org/10.1109/jssc.2007.900764.
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Lyon, Maureen, Daniel H. Grossoehme, Justin N. Baker, Sarah Friebert, Yao Cheng, Jody Chrastek, Jessica Thompkins, Matthew Tweddle, Jichuan Wang, and Jennifer Needle. "Relationship of spiritual constructs to mental health PROs in adolescents with cancer." Journal of Clinical Oncology 37, no. 31_suppl (November 1, 2019): 136. http://dx.doi.org/10.1200/jco.2019.37.31_suppl.136.
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136 Background: Global beliefs and goals form a meaning system, which plays a role in adjusting to stressors like cancer. Spirituality (search for the sacred) is a meaning system that can play a role in adolescent coping, and psychosocial adjustment to chronic disease. When malignancies occur during adolescence, there are long-term consequences to adjustment, functioning, and disease self-management. Methods: Data were obtained from 126 adolescents diagnosed with cancer at various stages and 4 sites in a longitudinal pediatric advance care planning intervention trial. Scales used: demographic; 2 spiritual scales (Brief-MMRS and FACIT-Sp v4); and 2 emotional PROMIS items (anxiety and depression). Bivariate relationships were analyzed. Structural equation modeling examined the relationship between spiritual and PROMIS items. Bootstrap with 1000 resamples was applied to due to sample size. Results: Mean age was 16.9 years (range: 14-20), with a mean time since diagnosis of 77 months (range: 1-232); 21% were on active treatment. The majority were female (57%) and white (79%). Most identified as spiritual (89%) and religious (83%). When asked if they believed they will be spiritually healed from cancer by a miracle, 49% reported “yes.” Adolescents viewing cancer as God’s punishment were more likely to have high depression (p = 0.03). Very or moderately spiritual teens were more likely to have high anxiety and high depression (p = 0.02). Meaning/peace (FACIT-Sp subscale) mediated feeling God’s presence on anxiety (β = -3.5; 95% CI: -9.2, -0.48) and depression (β = -4.6; 95%CI: -10.7, -1.1); and mediated religious identification on anxiety (β = -3.1; 95%CI:-6.9, -0.6) and depression (β = -4.1; 95%CI:-9.3,-0.24). Conclusions: Our findings are consistent with adult literature and a single longitudinal study of teens with cancer: spiritual distress (cancer is God’s punishment) is associated with poorer mental health outcomes, and meaning with positive outcomes. Adolescent anxiety and depression were inversely related to feeling God’s presence, and to identifying as religious; this effect was mediated by their sense of meaning/peace. Meaning-making is a modifiable process, opening a novel focus for intervention development. Clinical trial information: NCT02693665.
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Mints, Yuliya, Hirad Yarmohammadi, Irfan M. Khurram, Hana Hoyt, Rozann Hansford, Stefan L. Zimmerman, Steven J. Steinberg, et al. "Association of Common Variations on Chromosome 4q25 and Left Atrial Volume in Patients with Atrial Fibrillation." Clinical Medicine Insights: Cardiology 9 (January 2015): CMC.S21712. http://dx.doi.org/10.4137/cmc.s21712.
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Aims Recent studies have shown that several genetic variants near the PITX2 locus on chromosome 4q25 are associated with atrial fibrillation (AF). However, the mechanism that mediates this association remains unclear. Basic murine studies suggest that reduced PITX2 expression is associated with left atrial dilatation. We sought to examine the association between single nucleotide polymorphisms (SNPs) near PITX2 and left atrial size in patients with AF. Methods We prospectively enrolled 96 consecutive patients (mean age 60 ± 10 years, 72% male) with drug-resistant AF (57% paroxysmal, 38% persistent, and 5% long-standing persistent) who underwent catheter ablation. Following DNA extraction from blood obtained pre-operatively, SNPs rs10033464 and rs2200733 were genotyped using the Sequenom MassARRAY. Left atrial volume (LAV) was determined using three-dimensional imaging (CT or MRI prior to first ablation) and by investigators blinded to genotype results. Results The minor allele frequencies at SNPs rs10033464 and rs2200733 were 0.14 and 0.25, respectively. Using multivariable linear regression, homozygosity for the minor allele at rs10033464 (recessive model) was independently associated with larger LAV ( P = 0.002) after adjustment for age, gender, BMI, height, type, and duration of AF, left ventricular ejection fraction, history of hypertension, valve disease, and antiarrhythmic drug use. The strength of the association was reconfirmed in a bootstrap study with 1000 resamplings. In contrast, no association was found between rs2200733 variant alleles and LAV. Conclusion SNP rs10033464 near the PITX2 locus on 4q25 is associated with LAV. Left atrial dilatation may mediate the association of common variants at 4q25 with AF.
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P, Xenos, Nektarios M, Constantopoulos A, and Yfantopoulos J. "Two-stage hospital efficiency analysis including qualitative evidence: A Greek case." Journal of Hospital Administration 5, no. 3 (January 26, 2016): 1. http://dx.doi.org/10.5430/jha.v5n3p1.
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Background: The European Union health policy agenda stresses the importance of environmental and qualitative factors in structural hospital reforms. In response to the economic crisis, both cost containment and performance improvements of the Greek hospital sector, have become a pertinent issue for overall reforms.Objective: The study examines the efficiency of 112 Greek public hospitals, by applying bootstrapping techniques and investigating the effect of contextual factors on hospital efficiency. Furthermore, the effect of qualitative evidence, on hospital efficiency is explored by focusing on a subset of 28 large hospitals.Methods: The quality aspects of the Greek hospitals are investigated by applying two models of Data Envelopment Analysis (DEA), augmented by bootstrapping techniques, in order to assess the importance of quality dimensions on the efficiency of hospital scores. In addition, two Tobit regression models are estimated assessing the contribution of contextual factors, in the efficiency and bias-corrected efficiency scores.Results: Efficiency analysis indicated that only 23.2% of the hospitals are fully efficient (0.96-1.00), 37.5% are efficient (0.71-0.95) while 39.3% are inefficient (0.30-0.70). The Kolmogorov-Smirnov test, between the original and the bootstrap-corrected efficiency, indicates that their distributions are significantly different (p-value < .001). The environmental factors, influencing efficiency, are Occupancy Rate and the ratio between Outpatient Visits and Inpatient Days. Results indicate that the inclusion of Risk-Adjustment Mortality Rate significantly influences (p-value < .05) the efficiency of the hospitals.Conclusions: In the era of economic crisis, the inclusion of quality variables and the use of bootstrapping techniques provide a vital framework in assessing the efficiency of the hospital sector.
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Mu, Yi, Jonathan R. Edwards, Teresa C. Horan, Sandra I. Berrios-Torres, and Scott K. Fridkin. "Improving Risk-Adjusted Measures of Surgical Site Infection for the National Healthcare Safely Network." Infection Control & Hospital Epidemiology 32, no. 10 (October 2011): 970–86. http://dx.doi.org/10.1086/662016.
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Background.The National Healthcare Safety Network (NHSN) has provided simple risk adjustment of surgical site infection (SSI) rates to participating hospitals to facilitate quality improvement activities; improved risk models were developed and evaluated.Methods.Data reported to the NHSN for all operative procedures performed from January 1, 2006, through December 31, 2008, were analyzed. Only SSIs related to the primary incision site were included. A common set of patient- and hospital-specific variables were evaluated as potential SSI risk factors by univariate analysis. Some ific variables were available for inclusion. Stepwise logistic regression was used to develop the specific risk models by procedure category. Bootstrap resampling was used to validate the models, and the c-index was used to compare the predictive power of new procedure-specific risk models with that of the models with the NHSN risk index as the only variable (NHSN risk index model).Results.From January 1, 2006, through December 31, 2008, 847 hospitals in 43 states reported a total of 849,659 procedures and 16,147 primary incisional SSIs (risk, 1.90%) among 39 operative procedure categories. Overall, the median c-index of the new procedure-specific risk was greater (0.67 [range, 0.59–0.85]) than the median c-index of the NHSN risk index models (0.60 [range, 0.51–0.77]); for 33 of 39 procedures, the new procedure-specific models yielded a higher c-index than did the NHSN risk index models.Conclusions.A set of new risk models developed using existing data elements collected through the NHSN improves predictive performance, compared with the traditional NHSN risk index stratification.
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Nee, Robert, Evan Fisher, Christina M. Yuan, Lawrence Y. Agodoa, and Kevin C. Abbott. "Pre-End-Stage Renal Disease Care and Early Survival among Incident Dialysis Patients in the US Military Health System." American Journal of Nephrology 45, no. 6 (2017): 464–72. http://dx.doi.org/10.1159/000475767.
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Background: Previous reports showed an increased early mortality after chronic dialysis initiation among the end-stage renal disease (ESRD) population. We hypothesized that ESRD patients in the Military Health System (MHS) would have greater access to pre-ESRD care and hence better survival rates during this early high-risk period. Methods: In this retrospective cohort study, using the US Renal Data System database, we identified 1,256,640 patients initiated on chronic dialysis from January 2, 2004 through December 31, 2014, from which a bootstrap sample of 3,984 non-MHS incident dialysis patients were compared with 996 MHS patients. We assessed care by a nephrologist and dietitian, erythropoietin administration, and vascular access use at dialysis initiation as well as all-cause mortality as outcome variables. Results: MHS patients were significantly more likely to have had pre-ESRD nephrology care (adjusted OR [aOR] 2.9; 95% CI 2.3-3.7) and arteriovenous fistula used at dialysis initiation (aOR 2.2; 95% CI 1.7-2.7). Crude mortality rates peaked between the 4th and the 8th week for both cohorts but were reduced among MHS patients. The baseline adjusted Cox model showed significantly lower death rates among MHS vs. non-MHS patients at 6, 9, and 12 months. This survival advantage among MHS patients was attenuated after further adjustment for pre-ESRD nephrology care and dialysis vascular access. Conclusions: MHS patients had improved survival within the first 12 months compared to the general ESRD population, which may be explained in part by differences in pre-ESRD nephrology care and vascular access types.
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Ayalon, Liat. "Satisfaction with aging results in reduced risk for falling." International Psychogeriatrics 28, no. 5 (December 28, 2015): 741–47. http://dx.doi.org/10.1017/s1041610215001969.
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ABSTRACTBackground:Falls are highly frequent in older adults and are associated with increased morbidity and mortality. The present study was designed to assess the role of satisfaction with one's aging process as a predictor of the risk for falling over a four-year period and to identify potential mediators of this relationship.Methods:The Health and Retirement Study (HRS) is a US nationally representative sample of individuals over the age of 50 years and their spouse of any age. The present study was based on the 2008–2012 waves of the HRS. Analyses were restricted to 4,121 respondents over the age of 50 years, who had fall data in 2008 and 2012 and were eligible to complete the satisfaction with aging measure as part of the 2008 psychosocial questionnaire.Results:Overall, 38.1% of the sample reported having fallen at least once between 2006 and 2008 and 40.7% reported having fallen at least once between 2010 and 2012. Higher levels of satisfaction with aging in 2008 were found to be protective against falls assessed in 2012 (OR[95%CI] = 0.88[0.79–0.98]) even after adjustment for age, gender, education, ethnicity, medical status, functional status, cognitive functioning, walking speed, balance, vision, depressive symptoms, physical activities, and past falls. Bootstrap procedures have shown that the effect of satisfaction with aging on falls is partially accounted for through its effect on functional decline.Conclusions:The findings point to the important role of satisfaction with aging as a potential protective mechanism against falls. The results call for the development of psychosocial interventions to reduce falls in older adults.
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Jang, Ji-Hun, Seung-Hyun Jeong, and Yong-Bok Lee. "Population Pharmacokinetic Modeling of Zaltoprofen in Healthy Adults: Exploring the Dosage Regimen." Pharmaceuticals 16, no. 2 (January 22, 2023): 161. http://dx.doi.org/10.3390/ph16020161.
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Zaltoprofen is a drug used for various pain and inflammatory diseases. Scientific and quantitative dosage regimen studies regarding its clinical application are scarce. This study aimed to discover effective covariates related to interindividual pharmacokinetic variability through population pharmacokinetic modeling for zaltoprofen and to explore dosage regimens. The bioequivalence results of healthy Korean males, biochemical analysis, and CYP2C9 genotyping information were utilized in modeling. The established model has been sufficiently verified through a bootstrap, goodness-of-fit, visual predictive check, and normalized prediction distribution error. External data sets derived from the literature were used for further model validation. The final model could be used to verify the dosage regimen through multiple exposure simulations according to the numerical change of the selected covariates. Zaltoprofen pharmacokinetics could be explained by a two-compartment with a first-order absorption model. Creatinine clearance (CrCL) and albumin were identified as effective covariates related to interindividual zaltoprofen pharmacokinetic variability, and they had positive and negative correlations with clearance (CL/F), respectively. The differences in pharmacokinetics between individuals according to CYP2C9 genetic polymorphisms (*1/*1 and *1/*3) were not significant or valid covariates. The model simulation confirmed that zaltoprofen pharmacokinetics could significantly differ as the CrCL and albumin levels changed within the normal range. Steady-state plasma exposure to zaltoprofen was significantly reduced in the group with CrCL and albumin levels of 130 mL/min and 3.5 g/dL, respectively, suggesting that dose adjustment may be necessary. This study is useful to guide precision medicine of zaltoprofen and provides scientific quantitative judgment data for its clinical applications.
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Leoni, Matteo Luigi Giuseppe, Luisa Lombardelli, Davide Colombi, Elena Giovanna Bignami, Benedetta Pergolotti, Francesca Repetti, Matteo Villani, et al. "Prediction of 28-day mortality in critically ill patients with COVID-19: Development and internal validation of a clinical prediction model." PLOS ONE 16, no. 7 (July 13, 2021): e0254550. http://dx.doi.org/10.1371/journal.pone.0254550.
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Background COVID-19 pandemic has rapidly required a high demand of hospitalization and an increased number of intensive care units (ICUs) admission. Therefore, it became mandatory to develop prognostic models to evaluate critical COVID-19 patients. Materials and methods We retrospectively evaluate a cohort of consecutive COVID-19 critically ill patients admitted to ICU with a confirmed diagnosis of SARS-CoV-2 pneumonia. A multivariable Cox regression model including demographic, clinical and laboratory findings was developed to assess the predictive value of these variables. Internal validation was performed using the bootstrap resampling technique. The model’s discriminatory ability was assessed with Harrell’s C-statistic and the goodness-of-fit was evaluated with calibration plot. Results 242 patients were included [median age, 64 years (56–71 IQR), 196 (81%) males]. Hypertension was the most common comorbidity (46.7%), followed by diabetes (15.3%) and heart disease (14.5%). Eighty-five patients (35.1%) died within 28 days after ICU admission and the median time from ICU admission to death was 11 days (IQR 6–18). In multivariable model after internal validation, age, obesity, procaltitonin, SOFA score and PaO2/FiO2 resulted as independent predictors of 28-day mortality. The C-statistic of the model showed a very good discriminatory capacity (0.82). Conclusions We present the results of a multivariable prediction model for mortality of critically ill COVID-19 patients admitted to ICU. After adjustment for other factors, age, obesity, procalcitonin, SOFA and PaO2/FiO2 were independently associated with 28-day mortality in critically ill COVID-19 patients. The calibration plot revealed good agreements between the observed and expected probability of death.
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Patten, S. B., J. V. A. Williams, D. H. Lavorato, J. L. Wang, N. Jetté, T. T. Sajobi, K. M. Fiest, and A. G. M. Bulloch. "Patterns of association of chronic medical conditions and major depression." Epidemiology and Psychiatric Sciences 27, no. 1 (October 27, 2016): 42–50. http://dx.doi.org/10.1017/s204579601600072x.
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Aims.Age and sex-related patterns of association between medical conditions and major depressive episodes (MDE) are important for understanding disease burden, anticipating clinical needs and for formulating etiological hypotheses. General population estimates are especially valuable because they are not distorted by help-seeking behaviours. However, even large population surveys often deliver inadequate precision to adequately describe such patterns. In this study, data from a set of national surveys were pooled to increase precision, supporting more precise characterisation of these associations.Methods.The data were from a series of Canadian national surveys. These surveys used comparable sampling strategies and assessment methods for MDE. Chronic medical conditions were assessed using items asking about professionally diagnosed medical conditions. Individual-level meta-analysis methods were used to generate unadjusted, stratified and adjusted prevalence odds ratios for 11 chronic medical conditions. Random effects models were used in the meta-analysis. A procedure incorporating rescaled replicate bootstrap weights was used to produce 95% confidence intervals.Results.Overall, conditions characterised by pain and inflammation tended to show stronger associations with MDE. The meta-analysis uncovered two previously undescribed patterns of association. Effect modification by age was observed in varying degrees for most conditions. This effect was most prominent for high blood pressure and cancer. Stronger associations were found in younger age categories. Migraine was an exception: the strength of association increased with age, especially in men. Second, especially for conditions predominantly affecting older age groups (arthritis, diabetes, back pain, cataracts, effects of stroke and heart disease) confounding by age was evident. For each condition, age adjustment resulted in strengthening of the associations. In addition to migraine, two conditions displayed distinctive patterns of association. Age adjusted odds ratios for thyroid disease reflected a weak association that was only significant in women. In epilepsy, a similar strength of association was found irrespective of age or sex.Conclusions.The prevalence of MDE is elevated in association with most chronic conditions, but especially those characterised by inflammation and pain. Effect modification by age may reflect greater challenges or difficulties encountered by young people attempting to cope with these conditions. This pattern, however, does not apply to migraine or epilepsy. Neurobiological changes associated with these conditions may offset coping-related effects, such that the association does not weaken with age. Prominent confounding by age for several conditions suggests that age adjustments are necessary in order to avoid underestimating the strength of these associations.
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Kuang, Yachuan, Pengcheng Liu, Qishi Zhou, Feiyang Fu, and Wei Li. "Analysis Method of Design Strengths of P. edulis Bamboo." Forests 13, no. 4 (March 29, 2022): 526. http://dx.doi.org/10.3390/f13040526.
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In order to determine the design strengths of P. edulis bamboo material, this research carried out a series of material tests on the full-culm P. edulis bamboo specimens, including compression tests parallel to the grain, bending tests, tension tests parallel to the grain, shear tests parallel to the grain and compression tests perpendicular to the grain. The standard values of different strengths for bamboo material were obtained by the Bootstrap method. The influence of the load combination and load effect ratio on the relationship between reliability index β and resistance factor γR was analyzed. A method for calculating the target reliability index of bending strength was proposed. The design strengths of the P. edulis bamboo material were determined and the adjustment method considering different design situations was also put forward. The research results show that the target reliability of the bending strength of bamboo material is suggested to be 3.57. With the same β value, γR is the maximum under the combination of constant load + snow load, and γR is the minimum under the combination of constant load + live load on the office building floor. Under the same load combination and load ratio, the shear strength along the grain has the maximum γR and the compression strength along the grain has the minimum γR. The design strengths of the P. edulis bamboo material were determined by the larger γR of two cases (one is that the load ratio of constant load over live load on the residential building floor is 1.0 and another is that the constant load over live load on the office building floor is 1.0). The design strengths can provide reference for the design and application of bamboo structure.