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Journal articles on the topic 'Preliminary test estimator (PTE)'

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Published: 4 June 2021

Last updated: 19 February 2022

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1

Zakerzadeh, Hojatollah, Ali Akbar Jafari, and Mahdieh Karimi. "Optimal Shrinkage Estimations for the Parameters of Exponential Distribution Based on Record Values." Revista Colombiana de Estadística 39, no. 1 (January 18, 2016): 33–44. http://dx.doi.org/10.15446/rce.v39n1.55137.

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<p>This paper studies shrinkage estimation after the preliminary test for the parameters of exponential distribution based on record values. The optimal value of shrinkage coefficients is also obtained based on the minimax regret criterion. The maximum likelihood, pre-test, and shrinkage estimators are compared using a simulation study. The results to estimate the scale parameter show that the optimal shrinkage estimator is better than the maximum likelihood estimator in all cases, and when the prior guess is near the true value, the pre-test estimator is better than shrinkage estimator. The results to estimate the location parameter show that the optimal shrinkage estimator is better than maximum likelihood estimator when a prior guess is close<br />to the true value. All estimators are illustrated by a numerical example.</p>

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2

Gupta, V. P., and Umesh Singh. "Preliminary test estimator for life data." Microelectronics Reliability 25, no. 5 (January 1985): 881–87. http://dx.doi.org/10.1016/s0026-2714(85)80014-7.

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3

Gaber, Mohamed, and Edward J. Lusk. "A Vetting Protocol for the Analytical Procedures Platform for the AP-Phase of PCAOB Audits." Accounting and Finance Research 8, no. 4 (September 16, 2019): 43. http://dx.doi.org/10.5430/afr.v8n4p43.

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Study Context AS5[2017], issued by the Public Company Accounting Oversight Board, requires the use of Analytical Procedures [AP] at the Planning and Substantive Phases of Assurance Audits of firms traded on active exchanges. Logically, an aspect of this requirement is satisfied by using a Panel of the Client’s data at the Planning Phase to forecast the Client’s YE-closing values and then at the Substantive Phase to dispose the directional difference between the: [Actual Client’s YE-value and the AP-Forecasted YE-value]—the Disposition Phase. Research Focus To date, neither the PCAOB nor the AICPA have suggested a pilot-test paradigm to vet the AP-forecasting Protocol under consideration. To address this lacuna, we detail an AP: Decision Support System [AP:DSS] that offers to the Audit InCharge a two-stage pre-analysis AP-vetting [Pilot-Test] platform that employs False Negative [FN] and False Positive [FP] Profilers. In inferential analyses, the FP-Risk is usually benchmarked using the FN-Risk. Deliverables A comprehensive AP-vetting model is offered and illustrated using: (i) a preliminary estimator of a reasonable sample size, (ii) two Standard Forecasting Models: The Excel versions of the OLS Linear Two-parameter and the Moving Average Models, and (iii) a Benchmarking protocol. Unique in this AP:DSS vetting protocol is that the FP-risk is contexted by the FN-risk from the independent benchmark domain. This duality enhances the inferential impact of the vetting protocol as it uses separate variable sets. The AP:DSS is available at no cost as an e-Download.

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4

Ahmed, S. E., and R. J. Kulperger. "Asymptotic confidence intervals from a preliminary test estimator." Environmetrics 1, no. 3 (July 6, 2007): 295–303. http://dx.doi.org/10.1002/env.3170010304.

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5

Kulperger, R. J., and S. E. Ahmed. "A bootstrap theorem for a preliminary test estimator." Communications in Statistics - Theory and Methods 21, no. 7 (January 1992): 2071–82. http://dx.doi.org/10.1080/03610929208830898.

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6

Gupta, A. K., T. Nguyen, and L. Pardo. "Preliminary Phi-divergence test estimator for multinomial probabilities." Computational Statistics & Data Analysis 50, no. 7 (April 2006): 1749–73. http://dx.doi.org/10.1016/j.csda.2005.02.006.

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7

Salman, Abbas Najim, and Rana Hadi. "Preliminary test shrinkage estimators for the shape parameter of generalized exponential distribution." International Journal of Applied Mathematical Research 5, no. 4 (September 19, 2016): 162. http://dx.doi.org/10.14419/ijamr.v5i4.6573.

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The present paper deals with the estimation of the shape parameter α of Generalized Exponential GE (α, λ) distribution when the scale parameter λ is known, by using preliminary test single stage shrinkage (SSS) estimator when a prior knowledge available about the shape parameter as initial value due past experiences as well as optimal region R for accepting this prior knowledge.The Expressions for the Bias [B (.)], Mean Squared Error [MSE] and Relative Efficiency [R.Eff (.)] for the proposed estimator is derived.Numerical results about conduct of the considered estimator are discussed include study the mentioned expressions. The numerical results exhibit and put it in tables.Comparisons between the proposed estimator withe classical estimator as well as with some earlier studies were made to show the effect and usefulness of the considered estimator.

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8

Arumairajan, Sivarajah, and Pushpakanthie Wijekoon. "Preliminary Test Stochastic Restricted r-k Class Estimator and Preliminary Test Stochastic Restricted r-d Class Estimator in Linear Regression Model." British Journal of Mathematics & Computer Science 5, no. 2 (January 10, 2015): 204–27. http://dx.doi.org/10.9734/bjmcs/2015/13781.

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9

Johri, S. K., and V. P. Gupta. "Preliminary test estimator of average life in a life test experiment." Microelectronics Reliability 33, no. 1 (January 1993): 27–31. http://dx.doi.org/10.1016/0026-2714(93)90040-6.

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10

Hoque, Zahirul, Shahjahan Khan, and Jacek Wesolowski. "Performance of Preliminary Test Estimator Under Linex Loss Function." Communications in Statistics - Theory and Methods 38, no. 2 (January 2009): 252–61. http://dx.doi.org/10.1080/03610920802192471.

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11

Arumairajan, Sivarajah, and Pushpakanthie Wijekoon. "Principal Component Preliminary Test Estimator in the Linear Regression Model." Journal of Modern Applied Statistical Methods 15, no. 1 (May 1, 2016): 690–710. http://dx.doi.org/10.22237/jmasm/1462077180.

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12

Yüksel, Güzin, and Meral Çetin. "Outlier detection in a preliminary test estimator of the mean." Journal of Statistics and Management Systems 19, no. 4 (July 3, 2016): 605–15. http://dx.doi.org/10.1080/09720510.2016.1139851.

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13

Pandey, M., and S. K. Upadhyay. "Approximate prediction limit for weibull failure based on preliminary test estimator." Communications in Statistics - Theory and Methods 15, no. 1 (1986): 241–50. http://dx.doi.org/10.1080/03610928608829118.

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14

Chiou, Paul. "A Preliminary Test Estimator of Reliability in a Life-Testing Model." IEEE Transactions on Reliability R-36, no. 4 (October 1987): 408–10. http://dx.doi.org/10.1109/tr.1987.5222425.

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15

Arumairajan, S., and P. Wijekoon. "Generalized preliminary test stochastic restricted estimator in the linear regression model." Communications in Statistics - Theory and Methods 45, no. 20 (January 11, 2016): 6061–86. http://dx.doi.org/10.1080/03610926.2014.957850.

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16

Li, Yalian, Hu Yang, and Jianwen Xu. "More on the Preliminary Test Estimator in Almost Unbiased Liu Regression." Communications in Statistics - Theory and Methods 40, no. 13 (April 21, 2011): 2292–304. http://dx.doi.org/10.1080/03610921003778191.

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17

Xu, Jianwen, and Hu Yang. "Preliminary test almost unbiased ridge estimator in a linear regression model with multivariate Student-t errors." Acta et Commentationes Universitatis Tartuensis de Mathematica 15, no. 1 (December 11, 2020): 27–43. http://dx.doi.org/10.12697/acutm.2011.15.03.

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In this paper, the preliminary test almost unbiased ridge estimators of the regression coefficients based on the conflicting Wald (W), Likelihood ratio (LR) and Lagrangian multiplier (LM) tests in a multiple regression model with multivariate Student-t errors are introduced when it is suspected that the regression coefficients may be restricted to a subspace. The bias and quadratic risks of the proposed estimators are derived and compared. Sufficient conditions on the departure parameter ∆ and the ridge parameter k are derived for the proposed estimators to be superior to the almost unbiased ridge estimator, restricted almost unbiased ridge estimator and preliminary test estimator. Furthermore, some graphical results are provided to illustrate theoretical results.

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18

Karmous, Azza R., and Pranab K. Sen. "On Preliminary Test Isotonic M-Estimation of Multivariate Location Parameters." Calcutta Statistical Association Bulletin 37, no. 1-2 (March 1988): 1–16. http://dx.doi.org/10.1177/0008068319880101.

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Isotonic M-estimation of location parameters in the multivariate simple location model is considered under an orthant restriction on the parameters. The union-intersection principle and theory of M-estimation of location are incorporated in the formulation of some robust preliminary test and the derived estimator is studied under the null hypothesis as well as a sequence of local alternatives.

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19

Shukla, G. K., and P. Datta. "Comparison of the inverse estimator with the classical estimator subject to a preliminary test in linear calibration." Journal of Statistical Planning and Inference 12 (January 1985): 93–102. http://dx.doi.org/10.1016/0378-3758(85)90057-6.

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20

Karbalaee, Mohammad Hossein, Seyed Moahammad M. Tabatabaey, and Mohammed Arashi. "On the Preliminary Test Generalized Liu Estimator with Series of Stochastic Restrictions." Journal of the Iranian Statistical Society 18, no. 1 (June 1, 2019): 113–31. http://dx.doi.org/10.29252/jirss.18.1.113.

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21

Karbalaee, M. H., M. Arashi, and S. M. M. Tabatabaey. "Performance analysis of the preliminary test estimator with series of stochastic restrictions." Communications in Statistics - Theory and Methods 47, no. 1 (September 6, 2017): 1–17. http://dx.doi.org/10.1080/03610926.2017.1300275.

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22

Nagata, Yasushi, and Taichi Inaba. "Minimaxity of a preliminary test estimator for the mean of normal distribution." Annals of the Institute of Statistical Mathematics 37, no. 3 (December 1985): 437–42. http://dx.doi.org/10.1007/bf02481111.

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23

Rai, V. N., V. P. Gupta, and S. K. Saxena. "Modified preliminary test estimator for average life in one parameter exponential distribution." Microelectronics Reliability 28, no. 3 (January 1988): 379–82. http://dx.doi.org/10.1016/0026-2714(88)90393-9.

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24

Chaturvedi, Ajit, Suk-Bok Kang, and Ananya Malhotra. "Preliminary Test Estimators and Confidence Intervals for the Parametric Functions of the Moore and Bilikam Family of Lifetime Distributions Based on Records." Austrian Journal of Statistics 48, no. 4 (July 25, 2019): 58–89. http://dx.doi.org/10.17713/ajs.v48i4.844.

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We consider two measures of reliability functions namely R(t)=P(X>t) and P=P(X>Y) for the Moore and Bilikam (1978) family of lifetime distributions which covers fourteen distributions as specific cases. For record data from this family of distributions, preliminary test estimators (PTEs) and preliminary test confidence interval (PTCI) based on uniformly minimum variance unbiased estimator (UMVUE), maximum likelihood estimator (MLE), empirical Bayes estimator (EBE) are obtained for the parameter. The bias and mean square error (MSE) (exact and asymptotic) of the proposed estimators are derived to study their relative efficiency and through simulation studies we establish that PTEs perform better than ordinary UMVUE, MLE and EBE. We also obtain the coverage probability (CP) and the expected length of the PTCI of the parameter and establish that the confidence intervals based on MLE are more precise. An application of the ordinary preliminary test estimator is also considered. To the best of the knowledge of the authors, no PTEs have been derived for R(t) and P based on records and thus we define improved PTEs based on MLE and UMVUE of R(t) and P. A comparative study of different methods of estimation done through simulations establishes that PTEs perform better than ordinary UMVUE and MLE.

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25

Saleh, A. K. Md Ehsanes, M. Arashi, M. Norouzirad, and B. M. Goalm Kibria. "On shrinkage and selection: ANOVA model." Journal of Statistical Research 51, no. 2 (February 1, 2018): 165–91. http://dx.doi.org/10.47302/jsr.2017510205.

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This paper considers the estimation of the parameters of an ANOVA model when sparsity is suspected. Accordingly, we consider the least square estimator (LSE), restricted LSE, preliminary test and Stein-type estimators, together with three penalty estimators, namely, the ridge estimator, subset selection rules (hard threshold estimator) and the LASSO (soft threshold estimator). We compare and contrast the L2-risk of all the estimators with the lower bound of L2-risk of LASSO in a family of diagonal projection scheme which is also the lower bound of the exact L2-risk of LASSO. The result of this comparison is that neither LASSO nor the LSE, preliminary test, and Stein-type estimators outperform each other uniformly. However, when the model is sparse, LASSO outperforms all estimators except “ridge” estimator since both LASSO and ridge are L2-risk equivalent under sparsity. We also find that LASSO and the restricted LSE are L2-risk equivalent and both outperform all estimators (except ridge) depending on the dimension of sparsity. Finally, ridge estimator outperforms all estimators uniformly. Our finding are based on L2-risk of estimators and lower bound of the risk of LASSO together with tables of efficiency and graphical display of efficiency and not based on simulation.

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26

Arumairajan, Sivarajah, and Pushpakanthie Wijekoon. "More on the Preliminary Test Stochastic Restricted Liu Estimator in Linear Regression Model." Open Journal of Statistics 05, no. 04 (2015): 340–49. http://dx.doi.org/10.4236/ojs.2015.54035.

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27

Arumairajan, Sivarajah, and Pushpakanthie Wijekoon. "The generalized preliminary test estimator when different sets of stochastic restrictions are available." Statistical Papers 58, no. 3 (November 9, 2015): 729–47. http://dx.doi.org/10.1007/s00362-015-0723-x.

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28

Inaba, Taichi, and Yasushi Nagata. "Minimaxity and nonminimaxity of a preliminary test estimator for the multivariate normal mean." Annals of the Institute of Statistical Mathematics 39, no. 1 (December 1987): 49–54. http://dx.doi.org/10.1007/bf02491448.

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29

سلمان, عباس نجم, الاء ماجد, and مها عبد الجبار. "On Shrunken Estimation of Generalized Exponential Distribution." Journal of Economics and Administrative Sciences 17, no. 64 (December 1, 2011): 1. http://dx.doi.org/10.33095/jeas.v17i64.959.

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This paper deal with the estimation of the shape parameter (a) of Generalized Exponential (GE) distribution when the scale parameter (l) is known via preliminary test single stage shrinkage estimator (SSSE) when a prior knowledge (a0) a vailable about the shape parameter as initial value due past experiences as well as suitable region (R) for testing this prior knowledge. The Expression for the Bias, Mean squared error [MSE] and Relative Efficiency [R.Eff(×)] for the proposed estimator are derived. Numerical results about behavior of considered estimator are discussed via study the mentioned expressions. These numerical results displayed in annexed tables. Comparisons between the proposed estimator and the classical estimator as well as with some earlier studies were made to shown the effect and usefulness of the considered estimator.

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30

Sol, Marleen E., Janke F. de Groot, Maremka Zwinkels, J. M. Anne Visser-Meily, Cas L. J. J. Kruitwagen, and Olaf Verschuren. "Utrecht Pediatric Wheelchair Mobility Skills Test: Reliability, Validity, and Responsiveness in Youths Using a Manual Wheelchair." Physical Therapy 99, no. 8 (April 2, 2019): 1098–106. http://dx.doi.org/10.1093/ptj/pzz061.

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Abstract Background The assessment of wheelchair mobility skills (WMS) in youths using a manual wheelchair is important. More information is needed regarding the psychometric properties of the newly developed Utrecht Pediatric Wheelchair Mobility Skills Test (UP-WMST). Objective The purpose of this study was to evaluate the reliability, content validity, construct validity, and responsiveness of the UP-WMST 2.0 in youths using a manual wheelchair. Design This was a repeated-measurements, cross-sectional study. Methods A total of 117 children and adolescents who use a manual wheelchair participated in this study. The UP-WMST 2.0 contains the same 15 WMS items as the original UP-WMST but has an adaptation of the scoring method. Test-retest reliability was estimated in 30 participants. Content validity was assessed through floor and ceiling effect analyses. Construct validity was assessed through hypothesis testing. Preliminary estimates of responsiveness were assessed in 23 participants who participated in a WMS training program. Results Test-retest reliability analysis showed weighted Cohen kappa coefficients ranging from 0.63 to 0.98 for all but 1 item. The total UP-WMST 2.0 score had an intraclass correlation coefficient of 0.97. No floor or ceiling effects were detected. Independent-sample t test analysis confirmed our hypotheses regarding direction and difference in scores between age and diagnostic groups. Within-group analysis in the responsiveness study showed a positive significant change in UP-WMST 2.0 score (8.3 points). Limitations The small sample size used in the responsiveness study was a limitation of this study. Conclusions This study provided evidence of the test-retest reliability, content, and construct validity of the UP-WMST 2.0. It also provided initial evidence of the responsiveness of the UP-WMST 2.0 for measuring change in WMS in youths using a manual wheelchair.

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31

Cavaliere, Giuseppe, and Iliyan Georgiev. "EXPLOITING INFINITE VARIANCE THROUGH DUMMY VARIABLES IN NONSTATIONARY AUTOREGRESSIONS." Econometric Theory 29, no. 6 (August 13, 2013): 1162–95. http://dx.doi.org/10.1017/s0266466613000030.

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We consider estimation and testing in finite-order autoregressive models with a (near) unit root and infinite-variance innovations. We study the asymptotic properties of estimators obtained by dummying out “large” innovations, i.e., those exceeding a given threshold. These estimators reflect the common practice of dealing with large residuals by including impulse dummies in the estimated regression. Iterative versions of the dummy-variable estimator are also discussed. We provide conditions on the preliminary parameter estimator and on the threshold that ensure that (i) the dummy-based estimator is consistent at higher rates than the ordinary least squares estimator, (ii) an asymptotically normal test statistic for the unit root hypothesis can be derived, and (iii) order of magnitude gains of local power are obtained.

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32

Arumairajan, Sivarajah, and Pushpakanthie Wijekoon. "Improvement of the Preliminary Test Estimator When Stochastic Restrictions are Available in Linear Regression Model." Open Journal of Statistics 03, no. 04 (2013): 283–92. http://dx.doi.org/10.4236/ojs.2013.34033.

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33

Giles, David E. A., and Virendra K. Srivastava. "The exact distribution of a least squares regression coefficient estimator after a preliminary t-test." Statistics & Probability Letters 16, no. 1 (January 1993): 59–64. http://dx.doi.org/10.1016/0167-7152(93)90124-2.

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34

Chang, Xinfeng. "On preliminary test almost unbiased two-parameter estimator in linear regression model with student's t errors." Communications in Statistics - Theory and Methods 47, no. 3 (September 21, 2017): 583–600. http://dx.doi.org/10.1080/03610926.2017.1309433.

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35

Belaghi, R. Arabi, M. Arashi, and S. M. M. Tabatabaey. "On the Construction of Preliminary Test Estimator Based on Record Values for the Burr XII Model." Communications in Statistics - Theory and Methods 44, no. 1 (December 2014): 1–23. http://dx.doi.org/10.1080/03610926.2012.733473.

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36

Bressan, Paulo, and Cesar Da Costa. "An Indirect Estimator of Speed for a DC Motor Embedded in an Automotive Combustion Engine." European Journal of Engineering Research and Science 5, no. 9 (September 4, 2020): 1022–26. http://dx.doi.org/10.24018/ejers.2020.5.9.2096.

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This paper develops an estimator of speeds indirect for a DC motor embedded in an electrical water pump installed in internal combustion engines. The benefit of this technique is that the estimation framework doesn't require a dynamometer or machine-like coupling. The test results were based on the Motor Current Signal Analysis (MCSA) technique that is commonly used in an AC motor and has a great performance for measuring the rotational speed of electric motors. Two tests were used, one with DC motors using a dynamometer to validate the indirect reading of the rotation and another using the indirect estimator of speed developed in this work. This technique had positive results, regardless of the type of current sensor used. The preliminary outcomes from a research center model were introduced to justify the practicality of the proposed estimator of speed.

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37

Guarnaccia, Claudio. "EAgLE: Equivalent Acoustic Level Estimator Proposal." Sensors 20, no. 3 (January 27, 2020): 701. http://dx.doi.org/10.3390/s20030701.

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Road infrastructures represent a key point in the development of smart cities. In any case, the environmental impact of road traffic should be carefully assessed. Acoustic noise is one of the most important issues to be monitored by means of sound level measurements. When a large measurement campaign is not possible, road traffic noise predictive models (RTNMs) can be used. Standard RTNMs present in literature usually require in input several information about the traffic, such as flows of vehicles, percentage of heavy vehicles, average speed, etc. Many times, the lack of information about this large set of inputs is a limitation to the application of predictive models on a large scale. In this paper, a new methodology, easy to be implemented in a sensor concept, based on video processing and object detection tools, is proposed: the Equivalent Acoustic Level Estimator (EAgLE). The input parameters of EAgLE are detected analyzing video images of the area under study. Once the number of vehicles, the typology (light or heavy vehicle), and the speeds are recorded, the sound power level of each vehicle is computed, according to the EU recommended standard model (CNOSSOS-EU), and the Sound Exposure Level (SEL) of each transit is estimated at the receiver. Finally, summing up the contributions of all the vehicles, the continuous equivalent level, Leq, on a given time range can be assessed. A preliminary test of the EAgLE technique is proposed in this paper on two sample measurements performed in proximity of an Italian highway. The results will show excellent performances in terms of agreement with the measured Leq and comparing with other RTNMs. These satisfying results, once confirmed by a larger validation test, will open the way to the development of a dedicated sensor, embedding the EAgLE model, with possible interesting applications in smart cities and road infrastructures monitoring. These sites, in fact, are often equipped (or can be equipped) with a network of monitoring video cameras for safety purposes or for fining/tolling, that, once the model is properly calibrated and validated, can be turned in a large scale network of noise estimators.

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38

Shukla, Dhyanesh, and B. V. S. Sisodia. "Double sampling regression estimator of population mean subsequent to preliminary test of significance in finite population survey sampling." Journal of Statistical Theory and Practice 12, no. 2 (October 11, 2017): 325–35. http://dx.doi.org/10.1080/15598608.2017.1377652.

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39

Hoque, Z., B. Billah, and S. Khan. "On the Size Corrected Tests in Improved Estimation." Calcutta Statistical Association Bulletin 57, no. 3-4 (September 2005): 143–60. http://dx.doi.org/10.1177/0008068320050301.

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In this paper we propose shrinkage preliminary test estimator (SPTE) of the coefficient vector in the multiple linear regression model based on the size corrected Wald ( W), likelihood ratio ( LR) and Lagrangian multiplier ( LM) tests. The correction factors used are those obt,ained from degrees of freedom corrections to the estimate of the error variance and those obtained from the secondorder Edgeworth approximations to the exact distributions of the test statistics. The bias and weighted mean squared error (WMSE) fun ctions of the estimators are derived. With respect to WMSE, the relative efficiencies of the SPTEs relative to the maximum likelihood estimator are calculated. This study shows that the amount of conflict can be substantial when the three t ests are based on the same asymptotic chisquare critical value. The conflict among the SPTEs is due to the asymptotic tests not having the correct significance level. The Edgeworth size corrected W, LR and LM tests reduce the conflict remarkably.

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40

Wayte, Nicola, Derek Nancarrow, Euan Thomas Walpole, Guy Lampe, David Gotley, Bernard Mark Smithers, and Andrew Barbour. "Gene expression analysis of EAC in association with PET response." Journal of Clinical Oncology 30, no. 4_suppl (February 1, 2012): 50. http://dx.doi.org/10.1200/jco.2012.30.4_suppl.50.

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50 Background: Esophagectomy with preoperative chemotherapy or chemoradiotherapy are standard treatment regimens for localized esophageal adenocarcinoma (EAC). Early metabolic response to preoperative therapy (determined by FDG-PET scan) has been shown to predict histological response and survival. We present preliminary data from a randomized phase II trial of pre-operative cisplatin (C), 5-fluorouracil (F) and docetaxel ± radiotherapy based on early response to standard chemotherapy for resectable EAC. We present gene expression data for 22 patients with early FDG-PET response. Methods: Samples that were histologically proven invasive EAC and clinical stage T2/3 tumors were included in the analysis. All patients received C (day1) and F (days 1-4) chemotherapy. Early metabolic response was defined as >35% reduction in SUVmax on day 14 FDG-PET scan compared with baseline scan. Whole genome mRNA expression was obtained for pre-treatment biopsies using HumanHT-12v4 expression chips. Expression data was log2 transformed prior to robust spline normalization conducted with the lumi R package. Statistical analysis was performed in BRBarray. Results: There were 8 early PET responders and 14 early nonresponders to CF chemotherapy. Differentially expressed genes among PET responders and non-responders were identified using a random-variance t-test; 57 genes were identified as significantly differentially expressed between the two classes (p ≤ 0.001). A global test indicated significantly different expression profiles between the classes (p = 0.031). A gene classifier to predict PET response was explored and Support Vector Machines correctly classified 82% of samples with the prediction error estimated using leave-one-out cross-validation (p = 0.05). Epigenetic and apoptotic processes were significantly overrepresented in the gene list based on Gene Ontology analysis. Conclusions: This preliminary work supports a biological basis for the association between early metabolic PET response to preoperative therapy and survival in EAC patients. The list of differentially expressed genes may include potential biomarkers of treatment response and requires further investigation at the maturation of the phase II clinical trial for EAC.

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41

Halberg, DL. "PPR1: PRE-TEST OF A MARKOV MODEL TO ESTIMATE THE COST OF ILLNESS IN AMBULATORY PATIENTS: A PRELIMINARY ESTIMATE USING PHYSICIAN SURVEY DATA." Value in Health 2, no. 3 (May 1999): 221. http://dx.doi.org/10.1016/s1098-3015(11)71062-2.

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42

Shukla, D., and B. V. S. Sisodia. "Preliminary Test Regression Estimator When two Prior Values of Population Mean (μx) of an Auxiliary Variable (x) are Available." Communications in Statistics - Theory and Methods 44, no. 17 (September 2, 2015): 3541–48. http://dx.doi.org/10.1080/03610926.2013.841922.

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43

Mörkl, S., S. Lackner, G. Gorkiewicz, K. Kashofer, C. Blesl, A. Tmava, A. Oberascher, and S. Holasek. "Interplay of Gut Microbiota, Body Mass Index and Depression Scores in Anorexia Nervosa: Preliminary Data." European Psychiatry 41, S1 (April 2017): S92. http://dx.doi.org/10.1016/j.eurpsy.2017.01.287.

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IntroductionAnorexia nervosa (AN) is a lethal psychiatric disease with only narrow treatment possibilities. Recent study results point out, that gut microbiota might be a contributing factor in the development and persistence of AN through effects on the gut-brain-axis.MethodsWe used 16SRNA sequencing to characterize the composition and diversity of the gut microbiota of 18 AN patients, 19 normal weight controls and 19 athletes matched by age using stool samples. The QIIME-pipeline was used to assess the sequencing result. All participants completed an activity-questionnaire (IPAQ) and inventories to measure depression (BDI, HAMD).ResultsKruskal-Wallis test identified significant differences in alpha-diversity (Chao-1-estimator [P = 0.013], number of observed species [P = 0.027]) between groups. Spearman-Correlation revealed a significant correlation of number of observed species (r = 0.366, P = 0.006) Chao-1-estimator (r = 0.352, P = 0.008) and BMI (Fig. 1). Furthermore, a higher BMI was related to lower depression scores (r = 0.351, P < 0.001). Although there was a tendency of a negative correlation of BDI-scores and alpha-diversity (r = –0.180, P = 0.059), correlations with depression scores and IPAQ-scores did not reach significance level (Fig. 1).ConclusionsOur preliminary data demonstrate correlations of alpha-diversity and BMI. Further studies are needed to provide further insights in AN gut microbiota and its influence factors.Disclosure of interestThe authors have not supplied their declaration of competing interest.

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Son, J., D. Hou, and Z. Toth. "An assessment of Bayesian bias estimator for numerical weather prediction." Nonlinear Processes in Geophysics 15, no. 6 (December 16, 2008): 1013–22. http://dx.doi.org/10.5194/npg-15-1013-2008.

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Abstract. Various statistical methods are used to process operational Numerical Weather Prediction (NWP) products with the aim of reducing forecast errors and they often require sufficiently large training data sets. Generating such a hindcast data set for this purpose can be costly and a well designed algorithm should be able to reduce the required size of these data sets. This issue is investigated with the relatively simple case of bias correction, by comparing a Bayesian algorithm of bias estimation with the conventionally used empirical method. As available forecast data sets are not large enough for a comprehensive test, synthetically generated time series representing the analysis (truth) and forecast are used to increase the sample size. Since these synthetic time series retained the statistical characteristics of the observations and operational NWP model output, the results of this study can be extended to real observation and forecasts and this is confirmed by a preliminary test with real data. By using the climatological mean and standard deviation of the meteorological variable in consideration and the statistical relationship between the forecast and the analysis, the Bayesian bias estimator outperforms the empirical approach in terms of the accuracy of the estimated bias, and it can reduce the required size of the training sample by a factor of 3. This advantage of the Bayesian approach is due to the fact that it is less liable to the sampling error in consecutive sampling. These results suggest that a carefully designed statistical procedure may reduce the need for the costly generation of large hindcast datasets.

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Kim, Byung-Chul, Jingyu Kim, Kangsan Kim, Byung Hyun Byun, Ilhan Lim, Chang-Bae Kong, Won Seok Song, Jae-Soo Koh, and Sang-Keun Woo. "Preliminary Radiogenomic Evidence for the Prediction of Metastasis and Chemotherapy Response in Pediatric Patients with Osteosarcoma Using 18F-FDG PET/CT, EZRIN, and KI67." Cancers 13, no. 11 (May 28, 2021): 2671. http://dx.doi.org/10.3390/cancers13112671.

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Chemotherapy response and metastasis prediction play important roles in the treatment of pediatric osteosarcoma, which is prone to metastasis and has a high mortality rate. This study aimed to estimate the prediction model using gene expression and image texture features. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) images of 52 pediatric osteosarcoma patients were used to estimate the machine learning algorithm. An appropriate algorithm was selected by estimating the machine learning accuracy. 18F-FDG PET/CT images of 21 patients were selected for prediction model development based on simultaneous KI67 and EZRIN expression. The prediction model for chemotherapy response and metastasis was estimated using area under the curve (AUC) maximum image texture features (AUC_max) and gene expression. The machine learning algorithm with the highest test accuracy in chemotherapy response and metastasis was selected using the random forest algorithm. The chemotherapy response and metastasis test accuracy with image texture features was 0.83 and 0.76, respectively. The highest test accuracy and AUC of chemotherapy response with AUC_max, KI67, and EZRIN were estimated to be 0.85 and 0.89, respectively. The highest test accuracy and AUC of metastasis with AUC_max, KI67, and EZRIN were estimated to be 0.85 and 0.8, respectively. The metastasis prediction accuracy increased by 10% using radiogenomics data.

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De Luca, Giuseppe, and Jan R. Magnus. "Bayesian Model Averaging and Weighted-Average Least Squares: Equivariance, Stability, and Numerical Issues." Stata Journal: Promoting communications on statistics and Stata 11, no. 4 (December 2011): 518–44. http://dx.doi.org/10.1177/1536867x1201100402.

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In this article, we describe the estimation of linear regression models with uncertainty about the choice of the explanatory variables. We introduce the Stata commands bma and wals, which implement, respectively, the exact Bayesian model-averaging estimator and the weighted-average least-squares estimator developed by Magnus, Powell, and Prüfer (2010, Journal of Econometrics 154: 139–153). Unlike standard pretest estimators that are based on some preliminary diagnostic test, these model-averaging estimators provide a coherent way of making inference on the regression parameters of interest by taking into account the uncertainty due to both the estimation and the model selection steps. Special emphasis is given to several practical issues that users are likely to face in applied work: equivariance to certain transformations of the explanatory variables, stability, accuracy, computing speed, and out-of-memory problems. Performances of our bma and wals commands are illustrated using simulated data and empirical applications from the literature on model-averaging estimation.

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Salcman, Michael, Eiji Moriyama, Henry J. Elsner, Herman Rossman, Robert A. Gettleman, Gordon Neuberth, and Gregory Corradino. "Cerebral blood flow and the thermal properties of the brain: a preliminary analysis." Journal of Neurosurgery 70, no. 4 (April 1989): 592–98. http://dx.doi.org/10.3171/jns.1989.70.4.0592.

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✓ Safe and effective use of hyperthermia for the treatment of brain tumors requires precise control of the distribution of temperatures (that is, the thermal field) within the tumor and within the adjacent brain. Major influences upon the distribution of temperatures include the passive thermal properties of the brain, such as its specific heat (Cb), and the contribution of cerebral blood flow (CBF). Recently, an electrical-mechanical analog model of heat flow within the brain has been developed from which an expression for CBF has been derived: CBF = Cb/(τρc) where τ is the thermal decay constant, ρ is the density of blood, and c is its specific heat. To test this model a series of experiments was carried out in adult dogs in which stereotaxically implanted microwave antennas operating at 2450 MHz, fluoro-optical thermometry probes, and platinum electrodes were used to simultaneously measure CBF by thermal washout and hydrogen clearance techniques. The correlation coefficient for estimates of CBF derived by the two methods in 52 paired observations was 0.89. Measurements of CBF were more reliable at increased distances from the microwave antenna, since CBF is sensitive to the degree of temperature elevation (ΔT). The ratio of post-heating CBF to pre-heating CBF varies linearly with ΔT and has a correlation coefficient of 0.86. When values of CBF determined by the hydrogen clearance method were employed in the above equation, it was possible to derive Cb as 0.70 ± 0.08 cal/gm-°C. Use of this value for Cb in this equation produces estimates of CBF by thermal clearance that are within 10% of the values for CBF as measured by the hydrogen clearance method. It is concluded that this model of thermal flow within the brain may have heuristic value for treatment planning and that microwave antennas and fluoro-optical probes may represent a new methodology for the clinical estimation of CBF. These methods have recently been employed in patients undergoing combined hyperthermia and chemotherapy.

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Akinradewo, Opeoluwa Israel, Clinton Ohis Aigbavboa, and Ayodeji Emmanuel Oke. "Improving accuracy of road projects’ estimates in the Ghanaian construction industry." Journal of Financial Management of Property and Construction 25, no. 3 (July 29, 2020): 407–21. http://dx.doi.org/10.1108/jfmpc-11-2019-0087.

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Purpose The inaccuracy of preliminary estimates sometimes results in wasted development effort if the project is abandoned. To curb this menace, this study aims to assess the different measures to improve the accuracy of road project estimates. Design/methodology/approach Quantitative research design was used for this study, and questionnaire was designed to retrieve data from the target population. Engineers and quantity surveyors in Accra, Ghana formed the target population and were contacted by using an e-questionnaire through their professional bodies owing to location constraints. Descriptive and exploratory factor analyses were used in analysing the retrieved data. Mann–Whitney U non-parametric test was also used to compare the opinions of the respondents. Findings The study revealed that factors categorised as due diligence by estimator should be given more attention for accuracy of estimates to be improved. Research limitations/implications This study was limited to Accra, Ghana owing to time and distance constraint. Practical implications Proper consideration must be given to preliminary site investigation when preparing the estimates for road projects. This will provide the estimator with information on the physical features of the project environment. Originality/value Defined clusters of measures to improve estimate accuracy as highlighted in this study rather than merely ranked variables which are done by previous research studies will set the tone and provide insights for effective stakeholders’ actions. The study also bridges the gap between theory and practice by outlining how the findings can be implemented practically to achieve more accurate preliminary estimate for road projects. With efforts aligned with the core characteristics of each cluster, accuracy can be improved.

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Boyne, Pierce, Kari Dunning, Daniel Carl, Myron Gerson, Jane Khoury, Bradley Rockwell, Gabriela Keeton, et al. "High-Intensity Interval Training and Moderate-Intensity Continuous Training in Ambulatory Chronic Stroke: Feasibility Study." Physical Therapy 96, no. 10 (October 1, 2016): 1533–44. http://dx.doi.org/10.2522/ptj.20150277.

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AbstractBackgroundPoststroke guidelines recommend moderate-intensity, continuous aerobic training (MCT) to improve aerobic capacity and mobility after stroke. High-intensity interval training (HIT) has been shown to be more effective than MCT among healthy adults and people with heart disease. However, HIT and MCT have not been compared previously among people with stroke.ObjectiveThe purpose of this study was to assess the feasibility and justification for a definitive randomized controlled trial (RCT) comparing HIT and MCT in people with chronic stroke.DesignA preliminary RCT was conducted.SettingThe study was conducted in a cardiovascular stress laboratory and a rehabilitation research laboratory.PatientsAmbulatory people at least 6 months poststroke participated.InterventionBoth groups trained 25 minutes, 3 times per week, for 4 weeks. The HIT strategy involved 30-second bursts at maximum-tolerated treadmill speed alternated with 30- to 60-second rest periods. The MCT strategy involved continuous treadmill walking at 45% to 50% of heart rate reserve.MeasurementsMeasurements included recruitment and attendance statistics, qualitative HIT acceptability, adverse events, and the following blinded outcome variables: peak oxygen uptake, ventilatory threshold, metabolic cost of gait, fractional utilization, fastest treadmill speed, 10-Meter Walk Test, and Six-Minute Walk Test.ResultsDuring the 8-month recruitment period, 26 participants consented to participate. Eighteen participants were enrolled and randomly assigned to either the HIT group (n=13) or the MCT group (n=5). Eleven out of the 13 HIT group participants attended all sessions. Participants reported that HIT was acceptable and no serious adverse events occurred. Standardized effect size estimates between groups were moderate to very large for most outcome measures. Only 30% of treadmill speed gains in the HIT group translated into overground gait speed improvement.LimitationsThe study was not designed to definitively test safety or efficacy.ConclusionsAlthough further protocol optimization is needed to improve overground translation of treadmill gains, a definitive RCT comparing HIT and MCT appears to be feasible and warranted.

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Carlson, Kevin M., Kayla Tweedt, Miranda Strelecki, Ian Malaby, and Collin Seymour. "A Preliminary Examination of Shoulder Joint Function Following Shoulder Complex Training and In-Season Play in Youth Baseball Players." International Journal of Kinesiology and Sports Science 8, no. 4 (October 31, 2020): 59. http://dx.doi.org/10.7575/aiac.ijkss.v.8n.4p.59.

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Background: As shoulder care continues to be a concern for youth baseball players, coaches, parents, researchers and clinicians, shoulder complex care should remain a point of emphasis especially for in overhead athletes. The impact of throwing volume and shoulder care is important for us to understand. Objective: The purpose was to examine the changes in shoulder complex function during a playing season combined with shoulder complex training in young male baseball players. Methods: Eleven male baseball players (11-15 y/o) served as subjects. Pre-testing included shoulder joint internal/external rotation peak torque and average work as measured with isokinetic dynamometry (Biodex System 4Pro). Training over the 18-week project duration was Crossover Symmetry “Activation” and “Strength” protocols completed per manufacturer recommendations. Adherence was tracked via a weekly email sent to the subject’s guardian to self-report completed training. Post-testing was conducted at the conclusion of the 18th week. Paired sample t-tests compared pre-test and post-test mean differences for peak torque and average power (p<0.05). Results: All-subject average for training was 54 sessions over the 18 weeks. Estimated number of throws completed during practice and games over the 18 weeks was 8,400. For both testing speeds and for both internal and external shoulder joint rotation, peak torque increases ranged from ~50% for external rotation at 60 deg/s up to ~200% for internal rotation at 120 deg/s. Statistical differences (p<0.001) were noted between all pre-test and post-test internal and external rotation peak torque values. For both testing speeds and for both internal and external shoulder joint rotation, average power increases ranged from ~38% at 60 deg/s for external rotation up to ~200% at 120 deg/s for internal rotation. Statistical differences (p<0.005) were noted between all pre-test and post-test internal and external rotation average power values. Conclusions: Substantial increases in shoulder joint rotation peak torques and power were seen across the 18-week study duration. As this was a preliminary investigation, we have yet to discern if these increases are due to the shoulder complex training or volume of throwing that was completed.

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