Journal articles on the topic 'Trial-to-trial variation'
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Mocks, J., and T. Gasser. "New methods for dealing with trial-to-trial variation of single potentials." Electroencephalography and Clinical Neurophysiology 61, no. 3 (September 1985): S229. http://dx.doi.org/10.1016/0013-4694(85)90866-1.
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Terao, A., T. Hasbroucq, I. Mouret, J. Seal, and M. Akamatsu. "Why Does the Single Neuron Activity Change from Trial to Trial during Sensory-Motor Task?" Methods of Information in Medicine 36, no. 04/05 (October 1997): 322–25. http://dx.doi.org/10.1055/s-0038-1636882.
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Abstract:Single neuron activities from cortical areas of a monkey were recorded while performing a sensory-motor task (a choice reaction time task). Quantitative trial-by-trial analysis revealed that the timing of peak activity exhibited large variation from trial to trial, compared to the variation in the behavioral reaction time of the task. Therefore, we developed a multi-unit dynamic neural network model to investigate the effects of structure of neural connections on the variation of the timing of peak activity. Computer simulation of the model showed that, even though the units are connected in a cascade fashion, a wide variation exists in the timing of peak activity of neurons because of parallel organization of neural network within each unit.
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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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Turetsky, Bruce I., Jonathan Raz, and George Fein. "Estimation of Trial-to-Trial Variation in Evoked Potential Signals by Smoothing Across Trials." Psychophysiology 26, no. 6 (November 1989): 700–712. http://dx.doi.org/10.1111/j.1469-8986.1989.tb03176.x.
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Limpiti, Tulaya, Barry D. Van Veen, Hagai T. Attias, and Srikantan S. Nagarajan. "A Spatiotemporal Framework for Estimating Trial-to-Trial Amplitude Variation in Event-Related MEG/EEG." IEEE Transactions on Biomedical Engineering 56, no. 3 (March 2009): 633–45. http://dx.doi.org/10.1109/tbme.2008.2008423.
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Murrie, Daniel C., Marcus T. Boccaccini, Patricia A. Zapf, Janet I. Warren, and Craig E. Henderson. "Clinician variation in findings of competence to stand trial." Psychology, Public Policy, and Law 14, no. 3 (2008): 177–93. http://dx.doi.org/10.1037/a0013578.
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Hickey, Matthew S., David L. Costill, Glenn K. McConell, Jellrey J. Widrick, and Hirofumi Tanaka. "DAY TO DAY VARIATION IN TIME TRIAL CYCLING PERFORMANCE." Medicine & Science in Sports & Exercise 24, Supplement (May 1992): S104. http://dx.doi.org/10.1249/00005768-199205001-00620.
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Hickey, M., D. Costill, G. McConell, J. Widrick, and H. Tanaka. "Day to Day Variation in Time Trial Cycling Performance." International Journal of Sports Medicine 13, no. 06 (August 1992): 467–70. http://dx.doi.org/10.1055/s-2007-1021299.
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Kass, Robert E., and Valérie Ventura. "Spike Count Correlation Increases with Length of Time Interval in the Presence of Trial-to-Trial Variation." Neural Computation 18, no. 11 (November 2006): 2583–91. http://dx.doi.org/10.1162/neco.2006.18.11.2583.
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It has been observed that spike count correlation between two simultaneously recorded neurons often increases with the length of time interval examined. Under simple assumptions that are roughly consistent with much experimental data, we show that this phenomenon may be explained as being due to excess trial-to-trial variation. The resulting formula for the correlation is able to predict the observed correlation of two neurons recorded from primary visual cortex as a function of interval length.
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Evans, Elin, Helen Mayles, Olivia Frances Naismith, Emma Hall, Alison Tree, John Staffurth, and Isabel Syndikus. "Pretrial outlining quality assurance in PIVITOLBoost." Journal of Clinical Oncology 37, no. 7_suppl (March 1, 2019): 50. http://dx.doi.org/10.1200/jco.2019.37.7_suppl.50.
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50 Background: PIVOTALBoost is a Phase III randomised controlled trial (CRUK/16/018) of radiotherapy to prostate and pelvic nodes versus prostate alone with or without prostate boost. To minimise impact of target volume delineation (TVD) variation on trial outcome, pre-trial radiotherapy quality assurance (RTQA) was implemented to identify and correct potential variations. Methods: Participating centres offering a prostate boost submitted two pre-accrual outlining benchmark cases: one with a central zone boost (GTVpb) only and another with GTVpb (peripheral zone), CTVp/psv and CTVn. A detailed outlining protocol and diagnostic information were provided to centres. Submitted outlines were compared to consensus volumes created by the trial management group (TMG). The TMG deemed the volumes acceptable or as having acceptable or unacceptable variation. Detailed feedback was provided for each submission. Unacceptable variations required resubmission. Results: 32 investigators submitted pre-trial outlines. GTVpb was the most incorrectly outlined volume; 22 (69%) outliners had unacceptable errors for case 2 GTVpb, 17 (53%) for case 1 GTVpb. Most common GTVpb error was inferior extent of lesion followed by incorrect lesion outlined. 12 (38%) of outliners had unacceptable errors for CTVp/psv, most commonly due to delineation at the prostate apex. 8 (25%) outliners had unacceptable CTVn mostly due to incorrect vessel delineation. Of 26 (81%) outliners required to resubmit at least 1 case, 3(12%) required a second resubmission due to unacceptable errors on first resubmission. Conclusions: The majority of pre-trial outlining submissions had unacceptable errors requiring resubmission of at least one case. This was predominantly due to boost delineation error which is a relatively new skill for prostate clinical oncologists in the UK. This suggests robust on-trial RTQA is imperative to minimise further variation. Clinical trial information: ISRCTN80146950.
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Tanaka, Toshihisa, Itaru Yazawa, Katsushige Sato, Yoko Momose-Sato, and Kohtaro Kamino. "Consistency behind trial-to-trial variation in intrinsic optical responses to single-whisker movement in the rat D1-barrel cortex." Neuroscience Research 36, no. 3 (March 2000): 193–207. http://dx.doi.org/10.1016/s0168-0102(99)00117-0.
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Song, Xinxin, Robert G. V. Bramley, and Katherine J. Evans. "A method to position a simple strip trial to improve trial efficiency and maximise the value of vineyard variability for decision-making." OENO One 57, no. 1 (January 18, 2023): 97–107. http://dx.doi.org/10.20870/oeno-one.2023.57.1.5542.
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The main difficulties grapegrowers and consultants face in obtaining robust trial results include time and labour to collect data and land variability that confounds trial results. Spatial approaches that use whole-field designs, sensing technologies and geostatistical analysis enable more efficient data collection and account for the impact of spatial variation on crop responses while generating statistically robust results. However, the practical application of these approaches for vineyard trials requires affordable automation of measurements of viticultural variables and access to skills for geostatistics. A strip approach has been developed to simplify experimentation by allowing the farmer to use a single crop row to trial and analyse data in a spreadsheet. However, guidance is needed as to how to position trial strips in a vineyard block to reveal likely treatment effects across the entire block. Here, we investigated using a covariate to a response variable of interest to position a strip trial to infer treatment effects beyond the trial strip. Strip trials were simulated for two experiments: one comparing three treatments for vineyard floor management on grape yield and another comparing two spray programs for powdery mildew control. Useful covariates for yield or mildew severity were determined using correlation analyses. Trial results were analysed using a moving pairwise comparison of treatments and a moving average of the covariates. Simulated trial strips that incorporated a range of variation in a useful covariate close to that encountered in the whole block showed how yield or mildew severity varied with the covariates along the strips. Importantly, such results provided information about likely crop responses in other parts of the block according to variation in the covariates, thus contributing to better-informed decision-making. Compared to whole-field approaches, this strip approach is more efficient and simpler for growers to implement.
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Bi, Jian, Lynn Templeton-Janik, John M. Ennis, and Daniel M. Ennis. "Replicated difference and preference tests: how to account for inter-trial variation." Food Quality and Preference 11, no. 4 (July 2000): 269–73. http://dx.doi.org/10.1016/s0950-3293(99)00032-4.
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Scheibe, C., M. Ullsperger, W. Sommer, and H. R. Heekeren. "Effects of Parametrical and Trial-to-Trial Variation in Prior Probability Processing Revealed by Simultaneous Electroencephalogram/Functional Magnetic Resonance Imaging." Journal of Neuroscience 30, no. 49 (December 8, 2010): 16709–17. http://dx.doi.org/10.1523/jneurosci.3949-09.2010.
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McCaffery, K., J. Wardle, M. Nadel, and W. Atkin. "Socioeconomic variation in participation in colorectal cancer screening." Journal of Medical Screening 9, no. 3 (September 1, 2002): 104–8. http://dx.doi.org/10.1136/jms.9.3.104.
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OBJECTIVES: To investigate socioeconomic variation in participation in flexible sigmoidoscopy (FS) screening for colorectal cancer. DESIGN: A prospective study nested within a multicentre randomised controlled trial of the efficacy of FS screening for the prevention and early detection of colorectal cancer (the UK flexible sigmoidoscopy trial). SETTING: Glasgow, Scotland. PARTICIPANTS: 55–64 year old adults, registered with general practitioners participating in the FS trial. MAIN OUTCOME MEASURES: Screening participation measured at three levels: questionnaire return; interest in screening; attendance at screening. RESULTS: Socioeconomic deprivation was a strong predictor of participation. Return of the screening questionnaire, expression of interest in screening, and attendance at the test, were all lower in more deprived groups. CONCLUSIONS: These results highlight the need to consider ways to reduce inequalities in screening uptake, in parallel with the introduction of any new screening programmes, to avoid exacerbating social gradients in cancer mortality.
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Delaney, Hannah, Declan Devane, Andrew Hunter, Shaun Treweek, Nicola Mills, Carrol Gamble, and Valerie Smith. "A concept analysis of ‘trial recruitment’ using the hybrid model – Phase 1 findings." HRB Open Research 3 (December 21, 2020): 92. http://dx.doi.org/10.12688/hrbopenres.13173.1.
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Background: The International Committee of Medical Journal Editors (ICMJE) requires trials submitted for publication to be registered before enrolment of the first participant; however, there is ambiguity around the definition of recruitment and in anchoring the trial start date, end date, recruitment and enrolment, temporally to trial processes. There is potential for variation in how recruitment is reported and understood in trial protocols and trial reports. We report on Phase 1 of a concept analysis of ‘trial recruitment’ and develop a preliminary operational definition of ‘trial recruitment’. Methods: A concept analysis using the hybrid model. We searched randomised and non-randomised trial reports published between January 2018 and June 2019. Included studies were sourced from the five top journals in the category of medicine with the highest impact factor. We examined how recruitment was defined temporally to four time points; screening, consent, randomisation, and allocation. Results: Of the 150 trial reports analysed, over half did not identify a clear time point of when recruitment took place in relation to any of screening/consent/randomisation/allocation. The majority of the assessed trials provided a time frame in relation to the trial (i.e. start/end date), the process that this time frame referred to differed between studies. There was variation across studies in the terminology used to describe entry to the trial and often multiple terms were used interchangeably. Conclusion: There is ambiguity around temporal descriptions of ‘trial recruitment’ in health care journals. Informed by the findings of Phase 1, we developed a preliminary temporal operational definition of trial recruitment based on i) trial recruitment of an individual or cluster and ii) the trial recruitment period. In Phase 2 this definition will be discussed in focus groups with healthcare workers involved in designing/implementing/reporting on trials; to contribute to the final phase (analytical phase) of this concept analysis.
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Evans, Elin, Gareth Jones, Ganesh Radhakrishna, Maria A. Hawkins, Somnath Mukherjee, Rhydian Maggs, Ruby Ray, Tom David Lewis Crosby, and Sarah Gwynne. "On-trial radiotherapy quality assurance in NeoSCOPE: A randomised phase II trial of chemoradiotherapy in oesophageal cancer." Journal of Clinical Oncology 34, no. 4_suppl (February 1, 2016): 119. http://dx.doi.org/10.1200/jco.2016.34.4_suppl.119.
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119 Background: Failure to adhere to trial protocols for target volume delineation (TVD) within radiotherapy (RT) trials may have an adverse effect on, and potentially invalidate trial outcomes. NeoSCOPE, a UK phase II study RCT of two neo-adjuvant CRT regimens in oesophageal cancer, undertook prospective individual case-reviews (ICR) to identify and correct such variations. Methods: All participating centres had passed a pre-accrual outlining benchmark case with detailed feedback provided. Prospective ICR was undertaken for all patients. Real time review (feedback to centres within 3 working days) was performed on the first 20 patients recruited and the first case submitted from each participating centre. Subsequent cases were subject to ‘timely retrospective review’, with review within 2 weeks of the start of RT. Target volumes (including organ at risk), along with diagnostic information, were submitted in DICOM format to the RTQA centre. Each case was reviewed by an upper gastrointestinal radiation oncologist, against pre-determined acceptable and unacceptable variations, using a standardised proforma. Unacceptable variation required re-submission. The outlining reviews were complimented by prospective review of planning. Results: 83 cases were reviewed in total, 39 (47%) of which were real-time and 44 (53%) timely- retrospective. 9(11%) cases required re-submission, of which 6 were real-time reviews and 3 timely-retrospective. Delineation of the tumour (GTV) and elective nodal areas (CTVB) were the most common unacceptable variations. 29 (74%) of real time reviews were returned within 3 working days and 100% of retrospective returned by 3rdfraction. The review process did not result in any delay in starting treatment. Conclusions: Prospective review of outlining in the NeoSCOPE trial has enabled identification and correction of unacceptable variations from the protocol without introducing treatment delays. The reduction in the re-submission rate for timely-retrospective review cases suggests an educational benefit from the pre-trial RTQA and the real-time review process. Clinical trial information: NCT01843829.
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Zhou, Jin J., Juraj Koska, Gideon Bahn, and Peter Reaven. "Glycaemic variation is a predictor of all-cause mortality in the Veteran Affairs Diabetes Trial." Diabetes and Vascular Disease Research 16, no. 2 (March 2019): 178–85. http://dx.doi.org/10.1177/1479164119827598.
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Diabetes is associated with substantially increased mortality. Classic risk factors explain a portion of the excess of mortality in type 2 diabetes. The aim of this study was to examine whether visit-to-visit variation in fasting glucose and haemoglobin A1c values in the Veteran Affairs Diabetes Trial were associated with all-cause mortality in patients with type 2 diabetes in addition to other comorbidity conditions, hypoglycaemic events and adverse lifestyle behaviours. The Veteran Affairs Diabetes Trial was a randomized trial that enrolled 1791 military veterans who had a suboptimal response to therapy for type 2 diabetes to receive either intensive or standard glucose control. During the Veteran Affairs Diabetes Trial, fasting glucose and haemoglobin A1c were measured quarterly for up to 84 months. Variability measures included coefficient of variation and average real variability. We found that variability measures (coefficient of variation and average real variability) of fasting glucose were predictors of all-cause mortality, even after adjusting for comorbidity index, mean fasting glucose and adverse lifestyle behaviour during the study. Accounting for severe hypoglycaemia did not weaken this association. Our analysis indicates that in the Veteran Affairs Diabetes Trial, longitudinal variation in fasting glucose was associated with all-cause mortality, even when accounting for standard measures of glucose control as well as comorbidity and lifestyle factors.
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Morales, Laura, and Kelly Swarts. "Heritable and Climatic Sources of Variation in Juvenile Tree Growth in an Austrian Common Garden Experiment of Central European Norway Spruce Populations." Forests 13, no. 5 (May 22, 2022): 809. http://dx.doi.org/10.3390/f13050809.
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We leveraged publicly available data on juvenile tree height of 299 Central European Norway spruce populations grown in a common garden experiment across 24 diverse trial locations in Austria and weather data from the trial locations and population provenances to parse the heritable and climatic components of juvenile tree height variation. Principal component analysis of geospatial and weather variables demonstrated high interannual variation among trial environments, largely driven by differences in precipitation, and separation of population provenances based on altitude, temperature, and snowfall. Tree height was highly heritable and modeling the covariance between populations and trial environments based on climatic data led to more stable estimation of heritability and population × environment variance. Climatic similarity among population provenances was highly predictive of population × environment estimates for tree height.
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Thompson, A., S. A. Sullivan, M. Barley, S. O. Strange, L. Moore, P. Rogers, A. Sipos, and G. Harrison. "The DEBIT trial: an intervention to reduce antipsychotic polypharmacy prescribing in adult psychiatry wards – a cluster randomized controlled trial." Psychological Medicine 38, no. 5 (September 10, 2007): 705–15. http://dx.doi.org/10.1017/s003329170700147x.
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BackgroundClinical guidelines advise against prescribing more than one antipsychotic with limited exceptions. Despite this, surveys continue to report high antipsychotic polypharmacy rates. The aim of the study was to investigate the effectiveness of a multi-faceted intervention in reducing prescribing of antipsychotic polypharmacy on general adult psychiatry wards, compared with guidelines alone.MethodA pragmatic cluster randomized controlled trial recruited 19 adult psychiatric units (clusters) from the South West of England. Participants were all ward doctors and nurses. The multi-faceted intervention comprised: an educational/CBT workbook; an educational visit to consultants; and a reminder system on medication charts.ResultsThe odds of being prescribed antipsychotic polypharmacy in those patients prescribed antipsychotic medication was significantly lower in the intervention than control group when adjusted for confounders (OR 0.43, 95% CI 0.21–0.90, p=0.028). There was considerable between-unit variation in polypharmacy rates and in the change in rates between baseline and follow-up (5 months after baseline).ConclusionThe intervention reduced levels of polypharmacy prescribing compared to guidelines alone although the effect size was relatively modest. Further work is needed to elicit the factors that were active in changing prescribing behaviour.
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Al-Dirini, Rami M. A., Saulo Martelli, Dermot O'Rourke, Daniel Huff, Ju Zhang, John G. Clement, Thor Besier, and Mark Taylor. "Virtual trial to evaluate the robustness of cementless femoral stems to patient and surgical variation." Journal of Biomechanics 82 (January 2019): 346–56. http://dx.doi.org/10.1016/j.jbiomech.2018.11.013.
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Singh, Manish, Roland Rocafort, Cathy Cai, Kien Wei Siah, and Andrew W. Lo. "The reaction of sponsor stock prices to clinical trial outcomes: An event study analysis." PLOS ONE 17, no. 9 (September 2, 2022): e0272851. http://dx.doi.org/10.1371/journal.pone.0272851.
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We perform an event study analysis that quantifies the market reaction to clinical trial result announcements for 13,807 trials from 2000 to 2020, one of the largest event studies of clinical trials to date. We first determine the specific dates in the clinical trial process on which the greatest impact on the stock prices of their sponsor companies occur. We then analyze the relationship between the abnormal returns observed on these dates due to the clinical trial outcome and the properties of the trial, such as its phase, target accrual, design category, and disease and sponsor company type (biotechnology or pharmaceutical). We find that the classification of a company as “early biotechnology” or “big pharmaceutical” had the most impact on abnormal returns, followed by properties such as disease, outcome, the phase of the clinical trial, and target accrual. We also find that these properties and classifications by themselves were insufficient to explain the variation in excess returns observed due to clinical trial outcomes.
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Nordquist, B., J. Fischer, S. Y. Kim, S. M. Stover, T. Garcia-Nolen, K. Hayashi, J. Liu, and A. S. Kapatkin. "Effects of trial repetition, limb side, intraday and inter-week variation on vertical and craniocaudal ground reaction forces in clinically normal Labrador Retrievers." Veterinary and Comparative Orthopaedics and Traumatology 24, no. 06 (2011): 435–44. http://dx.doi.org/10.3415/vcot-11-01-0015.
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SummaryObjectives: To document the contributions of trial repetition, limb side, and intraday and inter-week measurements on variation in vertical and craniocaudal ground reaction force data.Methods: Following habituation, force and time data were collected for all four limbs of seven Labrador Retrievers during sets of five valid trot trials. Each set was performed twice daily (morning and afternoon), every seven days for three consecutive weeks. A repeated measures analysis of variance was used to determine the effects of limb, trial, intraday, and inter-week factors on ground reaction force data for the thoracic and pelvic limbs.Results: Of the four factors evaluated, variation due to trial repetition had the largest magnitude of effect on ground reaction forces. Trial within a set of data had an effect on all craniocaudal, but not vertical, ground reaction force variables studied, for the thoracic limbs. The first of five trials was often different from later trials. Some thoracic limb and pelvic limb variables were different between weeks. A limb side difference was only apparent for pelvic limb vertical ground reaction force data. Only pelvic limb craniocaudal braking variables were different between sets within a day.Discussion and clinical significance: When controlling for speed, handler, gait, weight and dog breed, variation in ground reaction forces mainly arise from trial repetition and inter-week data collection. When using vertical peak force and impulse to evaluate treatment, trial repetition and inter-week data collection should have minimal effect of the data.
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Vallury, Harish J., Michael A. Jones, Charles D. Hill, and Lloyd C. L. Hollenberg. "Quantum computed moments correction to variational estimates." Quantum 4 (December 15, 2020): 373. http://dx.doi.org/10.22331/q-2020-12-15-373.
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The variational principle of quantum mechanics is the backbone of hybrid quantum computing for a range of applications. However, as the problem size grows, quantum logic errors and the effect of barren plateaus overwhelm the quality of the results. There is now a clear focus on strategies that require fewer quantum circuit steps and are robust to device errors. Here we present an approach in which problem complexity is transferred to dynamic quantities computed on the quantum processor – Hamiltonian moments, ⟨Hn⟩. From these quantum computed moments, an estimate of the ground-state energy can be obtained using the ``infimum'' theorem from Lanczos cumulant expansions which manifestly corrects the associated variational calculation. With higher order effects in Hilbert space generated via the moments, the burden on the trial-state quantum circuit depth is eased. The method is introduced and demonstrated on 2D quantum magnetism models on lattices up to 5×5 (25 qubits) implemented on IBM Quantum superconducting qubit devices. Moments were quantum computed to fourth order with respect to a parameterised antiferromagnetic trial-state. A comprehensive comparison with benchmark variational calculations was performed, including over an ensemble of random coupling instances. The results showed that the infimum estimate consistently outperformed the benchmark variational approach for the same trial-state. These initial investigations suggest that the quantum computed moments approach has a high degree of stability against trial-state variation, quantum gate errors and shot noise, all of which bodes well for further investigation and applications of the approach.
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Qiao, Yao, G. Caleb Alexander, and Thomas J. Moore. "Globalization of clinical trials: Variation in estimated regional costs of pivotal trials, 2015–2016." Clinical Trials 16, no. 3 (March 29, 2019): 329–33. http://dx.doi.org/10.1177/1740774519839391.
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Background/Aims Despite the increasing globalization of clinical trials, little is known regarding how the trial site costs vary around the world. We quantified the geographical distribution and regional cost differences for the clinical trials that established the benefits for new therapeutic drugs approved by the US Food and Drug Administration in 2015 and 2016. Methods We included all pivotal clinical trials for 59 new molecular entities approved by the US Food and Drug Administration in 2015 and 2016 that included at least one site in North America. We derived cost estimates from IQVIA’s CostPro, a global clinical trial cost-estimating tool used by pharmaceutical sponsors. We assessed the patient and site allocation of these trials across eight geographic regions. To quantify the region-specific cost differences, we conducted a within-trial comparison by expressing the estimated regional costs associated with the sites in each global region as a percent of the same costs in North America. We also estimated the percentage breakdown of regional cost components (pass-through, site management, regulatory, and study conduct costs) for each trial and for all endpoints reported the median and interquartile range. Results Overall, 127 pivotal clinical trials enrolled 91,415 patients from 13,264 sites. Most patients (60.3%) and sites (57.3%) were outside North America. A median of 66% of the total estimated trial costs (interquartile range: 60%–72%) were spent on regional tasks, with the largest share (53.3%) going directly to trial sites and the remainder going to other regional trial management tasks. Differences were greatest in four lower cost regions: Africa, with an estimated regional cost per site of 49% of North America (interquartile range: 44%–56%), Central Europe 50% (interquartile range: 41%–63%), Middle East 53% (interquartile range: 42%–64%) and Latin America 59% (interquartile range: 50%–70%). Overall, 90 (71%) of the 127 pivotal trials had a total of 3160 sites in these lower cost regions. In contrast, savings were more limited in Western Europe, Oceania, and Asia, where estimated regional costs were 78% of North America (interquartile range: 67%–89%). One-quarter of the trials with sites in Asia and Oceana did not achieve cost savings in those regions relative to North America. Conclusion Among this sample of pivotal trials for recently approved US Food and Drug Administration products, most patients and sites enrolled were outside of North America, with selection of regional sites having a significant impact on total trial costs.
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Zheng, Wei, Hengben Ma, Ming Zhang, Fengming Xue, Kexun Yu, Yong Yang, Shaoxiang Ma, et al. "Evaluation of the First Negative Ion-Based Cloud Seeding and Rain Enhancement Trial in China." Water 13, no. 18 (September 9, 2021): 2473. http://dx.doi.org/10.3390/w13182473.
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Negative ion-based cloud seeding has been shown to be an effective means in the laboratory. China’s first negative ion-based cloud seeding outfield trial was conducted in the northwestern interior. This paper briefly introduces the principle of the ion-based precipitation enhancement, and the trial location is described. The design of the ionization system and meteorological monitoring network are presented. The implementation plan of the outfield trial is explained. In addition, the evaluation of experimental effects is detailed in this paper. We designed various analytical methods to investigate both the overall precipitation variation of the experimental area and the precipitation variation within the experimental area. The overall precipitation of the experimental area was predicted using a neural network, and then the actual precipitation was compared with the predicted precipitation to evaluate the effectiveness of the experiment. The effectiveness of the experiment was also evaluated using historical precipitation data and the result of the randomized comparative trial. This paper also explores the effects of geographic location differences and wind direction differences on the precipitation differences within the trial area. The changes in the number of negative ions and clouds in the sky were also analyzed. From these analyses, we obtained quantitative assessment results. These results could indicate that the outfield trial basically met the expected requirements, which is to increase the rainfall of the trial area by 20%.
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Togatorop, Romian, and Dewi Endriani. "PENGEMBANGAN VARIASI LATIHAN TENDANGAN USHIRO MAWASHI GERI PADA ATLET KUMITE KARATE." Journal Physical Health Recreation 2, no. 2 (June 27, 2022): 172–79. http://dx.doi.org/10.55081/jphr.v2i2.650.
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This study aims to develop variations of the ushiro mawashi geri kick exercise in kumite karate athletes. The population in this study were 5 HKBP Sidorame dojo athletes, 8 dojo athletes at SMP N 31 Medan, 7 dojo athletes in Medan Tuntungan, and 13 dojo athletes Hedi GOJUKAI. The development of this exercise variation was first validated by 3 experts, 1 coach expert, 1 referee expert, and 1 sports expert where the validation percentage was 92%-94%. The method used is the research and development (R&D) method. The results of the small group trial involving 13 athletes from the HKBP Sidorame dojo and the SMP N 31 Medan dojo showed that the variation of the ushiro mawashi geri kick exercise met the criteria to be continued in the large group trial because the percentage score of each aspect was between 89.23%-100%. The results of a large group trial of 20 athletes at the Hedi GOJUKAI dojo and the Medan Tuntungan dojo showed that the variation of the ushiro mawashi geri kick exercise met the criteria for continuing in the manufacture of mass products because the percentage of each aspect was between 88%-95%. From the results it was concluded that the variation of the ushiro mawashi geri kick exercise was more effective and efficient, because it was very important in supporting the athlete's achievement, besides that the exercise was not boring and became input for karate coaches throughout Indonesia.
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Christopherson, R., K. E. James, M. Tableman, P. Marshall, A. L. Kline, and F. E. Johnson. "Long-term survival following colon cancer surgery: Variation associated with choice of anesthesia." Journal of Clinical Oncology 25, no. 18_suppl (June 20, 2007): 17015. http://dx.doi.org/10.1200/jco.2007.25.18_suppl.17015.
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17015 Background: VA Cooperative Trial 345 randomized patients having abdominal surgery to unsupplemented general anesthesia (UGA) or epidural-supplemented general anesthesia (ESGA). The long-term clinical significance of the type of anesthesia for patients having surgery for colon cancer has not been well studied. We compared survival of patients with colon cancer randomized to ESGA to survival of those randomized to UGA. Methods: Survival of colon cancer patients was not a primary trial end point. We conducted a post hoc analysis of the colon cancer patients in the trial using TNM staging data from patient records. A Cox survival model was used to test the effects of pathological stage, type of anesthesia and other covariates on survival. Results: 177 patients were evaluable. In both trial arms, survival was similar (P = 0.23) until 4.56 years. After 4.56 years, patients assigned to UGA had significantly better survival (P = 0.01). In both trial arms, the survival in patients without metastases was similar initially, but those who received UGA had significantly better survival later. A similar statistically significant pattern was evident in patients with metastases. The long-term survival benefit of UGA was even more pronounced among patients with metastases and a diagnosis of alcoholism. Conclusions: This study provides the first evidence that ESGA may worsen long-term survival in colon cancer patients, especially those with metastases and alcoholism. Epidural anesthesia affects visceral blood flow, immunological parameters, post-operative pain and other physiological variables, which could explain these findings. Additional studies to confirm or refute these unexpected findings are warranted. No significant financial relationships to disclose.
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Retee, NN, MMH Mondal, AI Omar, K. Periasamy, JF Garcia, DR Notter, and MO Faruque. "Resistance of Black Bengal goat to Haemonchus contortus." Progressive Agriculture 30, no. 1 (July 17, 2019): 55–64. http://dx.doi.org/10.3329/pa.v30i1.42209.
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Artificial challenge trial and field trial were carried out in two populations of Black Bengal goat in Bangladesh to evaluate the resistance to Haemonchus Contortus-a major gastrointestinal nematode in goat. Artificial challenge trial revealed that there was no difference in susceptibility of H. contortus in Black Bengal goat of hilly region (BBH) and Black Bengal goat of western region (BBW). In absence of parasitic infection, growth rate of kids of both populations were almost equal. Field trial was conducted with kids of BBW population to find out the within breed variation. Numerically, there was variation among the individuals for parasitic load however the results were statistically insignificant (p > 0.05). At individual level, the parasite load ranged from 100 to 400 eggs per gram (epg). The location of villages, age and sex of kids did not influence on the parasitic load of kids. There was no interaction for location, age and sex for body weight at day 8. The Packed Cell Volume and Hemoglobin values differed significantly (p < 0.01) due to age of kids at day 8 and 28 after deworming. The results indicate that Black Bengal goat can be considered as resilience to H. contortus.
Progressive Agriculture 30 (1): 55-64, 2019
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Salajegheh, A., A. Link, C. Elster, M. Burghoff, T. Sander, L. Trahms, and D. Poeppel. "Systematic latency variation of the auditory evoked M100: from average to single-trial data." NeuroImage 23, no. 1 (September 2004): 288–95. http://dx.doi.org/10.1016/j.neuroimage.2004.05.022.
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Villarroel, Morris, Genaro C. Miranda-de la Lama, Rubén Bermejo-Poza, Concepción Pérez, Elisabet González-de Chávarri, Fernando Torrent, and Jesús De la Fuente. "Effects of Randomly Fired Underwater Currents as an Occupational Enrichment Program in Rainbow Trout (Oncorhynchus mykiss)." Water 13, no. 21 (November 1, 2021): 3057. http://dx.doi.org/10.3390/w13213057.
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Occupational enrichment (OE) is directed at introducing variations in the tank water so that fish can exercise as they do in the wild. Two trials were carried out to test the effects of randomly fired underwater currents (RFC) on rainbow trout (Oncorhynchus mykiss) maintained in tanks in a recirculation system, using 1226 trout distributed in two independent trials. In Trial 1, fingerling trout (n = 6 tanks, n = 40 fish per tank) were classified into two groups based on low (13%) or high (30%) coefficient of variation in live weight (CV), and exposed to RFC or no currents (controls). In Trial 2, adult trout (n = 12 tanks, n = 20 fish per tank) were either exposed to RFC or to a constant current (controls) from two submerged pumps. Both trials lasted four weeks. No significant differences in growth were observed between treatments in either trial. In Trial 1, RFC fish maintained a similar CV throughout the trial, while CV decreased in controls. Also, in Trial 1, plasma cortisol levels were higher and creatine phosphokinase (CPK) levels lower in tanks with a low initial CV. In Trial 2, the CV was lower in RFC trout, where cortisol levels were also significantly lower and triglycerides significantly higher. The results suggest that OE using RFC can have positive effects by helping to reduce stress levels, and provides fish with biologically meaningful environmental enrichment related to the natural history of the species.
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Viana, Tamires Rebeca Forte Viana, Gleicia Martins de Melo, Maria Vera Lucia Moreira Leitão Cardoso, Paulo César de Almeida, Lusiana Moreira de Oliveira, and Daisyanne Augusto de Sales Santos. "Pain in full term newborns submitted to music and swaddling during venipunctures." Rev Rene 21 (June 18, 2020): e43904. http://dx.doi.org/10.15253/2175-6783.20202143904.
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Objective: to compare pain scores in term newborns submitted to music and swaddling interventions during venipuncture. Methods: pilot study of a clinical trial, carried out with 11 newborns in rooming-in care who received venipunctures. The newborns were randomly allocated into two groups: Experimental (20 minutes of music + swaddling) and Control (swaddling). Newborns were filmed and pain was assessed by the Neonatal Facial Coding System at baseline, procedure, and initial recovery phases. Results: the Experimental Group at baseline, procedure (antisepsis, puncture, and milking), and recovery showed less pain reactions and lower heart rate mean and variation (p<0.05) than the Control Group. Conclusion: newborns who received the intervention of music combined with swaddling had less pain reactions and less variations in heart rate during venipuncture. Brazilian Clinical Trial Registry: RBR-8x8v2r.
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Ovenell-Roy, K. H., M. L. Nelson, J. A. Froseth, S. M. Parish, and E. L. Martin. "Variation in chemical composition and nutritional quality among barley cultivars for ruminants. 1. Steer finishing performance, diet digestibilities and carcass characteristics." Canadian Journal of Animal Science 78, no. 3 (September 1, 1998): 369–75. http://dx.doi.org/10.4141/a96-098.
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Inherent variability in chemical composition and nutritional value exists among barley (Hordeum vulgare L.) cultivars due to year grown, head morphology, growth habit and intended end use. Two trials were conducted to identify causal factors for variability among barley cultivars in animal performance, carcass characteristics, diet digestibility and digestible energy (DE) content. In feedlot trials, 144 large-frame beef steers (380 ± 1.6 kg in Trial 1, 372 ± 0.8 kg in Trial 2) were assigned within three weight blocks, eight to a pen, in a randomized complete block design and pens to treatments. Steers were fed a diet of 83% steam-rolled barley (Andre, Camelot, Clark, Cougbar, Harrington or Steptoe for 123 d in Trial 1; Boyer, Camelot, Clark, Harrington, Hesk or Steptoe for 119 d in Trial 2), 10% silage (wheat in Trial 1, oat in Trial 2), and 7% supplement on a dry matter (DM) basis. In Trial 1, Cougbar neutral detergent fiber (NDF) digestibility was significantly lower than Clark. Digestibility of other nutrients tended to be lowest for steers fed Cougbar and as a result, diet DE was lower (P < 0.05) for Cougbar than for Clark and Camelot. Diet DE and NDF digestibility were correlated (r = 0.69; P < 0.0001). Lower nutrient utilization by steers fed Cougbar resulted in lower performance. In Trial 2, steers fed Hesk had a poorer (P < 0.05) ratio of feed to gain than steers fed Camelot and Harrington and lower (P < 0.05) digestibility than steers fed Steptoe. In summary, data from these trials suggest that Cougbar and Steptoe are of lower nutritional value than other cultivars under the conditions of these studies. In these studies, digestibility of NDF was a major factor contributing to differences among cultivars. Key words: Barley, steers, digestibility, energy
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Roa, Sergio D., and Luis E. Muñoz. "Bicycle change strategy for uphill time-trial races." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 231, no. 3 (August 29, 2017): 207–19. http://dx.doi.org/10.1177/1754337117724310.
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In uphill time-trial cycling races, riders have to travel along routes characterized by high-gradient variations in the shortest time possible. Due to this gradient variation, the appropriate selection among time-trial bicycles and traditional road bicycles is essential to reduce the power demand. For some uphill courses, the bicycle selection is not necessarily unique, with the possibility of a bicycle change during the race to take advantage of the performance of each type of bicycle for specific sections of the route. In this study, a method for planning the bicycle-changing strategy is proposed. A dynamic model to predict the race time for two types of bicycles is implemented, and an optimization problem for minimizing the race time is presented. A case study is analyzed in which the uphill time-trial route of the Giro d’Italia 2014 is studied in the context of professional cyclists’ performance. It was found that the use of the bicycle change strategy led to a time saving of about 43 s with respect to the time obtained when using only a road bicycle. It was also found that a combination of the bicycle change strategy with an optimal pacing strategy led to a time saving of about 92 s.
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Pavlovic, Nenad, Bogoljub Zecevic, Milan Zdravkovic, Miroslav Ivanovic, and Milan Damjanovic. "Variability and heritability of average yield of onion bulb - Alium сeрa L." Genetika 35, no. 3 (2003): 149–54. http://dx.doi.org/10.2298/gensr0303149p.
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In order to investigate the variability of bulb yield, the trial was set up on an experimental plot of the Centre for Vegetable Crops in Smederevska Palanka during 1997 and 1998. The trial was performed by applying the method of random block system in five replications. Ten varieties of different geographical origins were included as the research material. The recorded values of the investigated features were determined by applying the variance analysis of a two-factorial trial model 2 (Hadzivukovic, 1991). The components of the phenotype variance, genotype and phenotype coefficient of variation and heritability in broad sense were estimated according to Singh and Chaudhary (1976). Significant variability was recorded for yield bulbs in both years of investigation. For this parameter, genotype variance was greater than the enviromental. Phenotype coefficient of variation (PCV) was greater than genotype coefficient of variation (GCV). Heritability confirmed that the genotype variability was stronger in the overall phenotype variability.
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Gömöry, D., L. Paule, and E. Gömöryová. "Effects of microsite variation on growth and adaptive traits in a beech provenance trial." Journal of Forest Science 57, No. 5 (May 16, 2011): 192–99. http://dx.doi.org/10.17221/88/2010-jfs.
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ABSTRACT: The effects of the within-trial spatial variation of environmental factors on phenotypic traits were studied in the Slovak plot of the international beech provenance trial coordinated by BFH Grosshansdorf with 32 provenances, established under a randomized complete block design with three adjacent blocks. Five indicators of soil properties (soil moisture, bulk density and pH) and microclimate (average daily temperature and temperature amplitude) were assessed at 96 points distributed over a 10 × 10 m grid and their values for the positions of individual trees were estimated by ordinary point kriging. The evaluation of phenotypic variation (height, diameter, Julian days of spring flushing and autumn leaf discoloration, vegetation period length, late frost damage) using a common two-way analysis of variance showed a significant provenance × block interaction effect indicating the heterogeneity of blocks. Analysis of covariance using single-tree kriging estimates of environmental variables as covariates showed that in addition to provenance, all phenotypic traits were significantly affected by microsite, especially by temperature fluctuation. Employing methods incorporating the spatial component in the evaluation of tree breeding field experiments is advocated.
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Ware, Russell E., Adam Lane, William H. Schultz, Hamayun Imran, Margaret T. Lee, Matthew M. Heeney, Clark Brown, et al. "Variation in Serial TCD Velocity Measurements in the TCD with Transfusions Changing to Hydroxyurea (TWiTCH) Trial." Blood 128, no. 22 (December 2, 2016): 1019. http://dx.doi.org/10.1182/blood.v128.22.1019.1019.
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Abstract Introduction: The multicenter phase 3 randomized clinical trial TCD With Transfusions Changing to Hydroxyurea (TWiTCH, NCT01425307) investigated whether hydroxyurea could maintain TCD velocities and prevent stroke in children with sickle cell anemia and abnormal TCD velocities. The trial was stopped early after reaching the primary endpoint, when the average TCD velocity in the alternative (hydroxyurea) arm was found to be non-inferior and even slightly better (138 versus 143 cm/sec) than the standard (transfusion) arm. A planned secondary analysis was to determine the variation in serial TCD velocity measurements for individual study participants, to document the normal TCD velocity fluctuations that occur and to inform the need for frequent TCD evaluations in this clinical setting. Methods: All TCD examinations collected in TWiTCH were analyzed for the maximum time-averaged mean velocity (TAMV) measured in the main intracranial arteries. TCD studies were performed by certified examiners using identical non-imaging instruments, no more than one week before a scheduled transfusion or phlebotomy procedure. Measurements on the index side, defined as the cerebral hemisphere with the higher mean arterial velocity at baseline assessment, were used for these statistical analyses. TCD values were analyzed according to four phases of the trial: (1) screening with three monthly TCD examinations performed at Weeks -8, -4, and 0 before randomization; (2) initial treatment period (hydroxyurea dose escalation with overlap transfusions or transfusions only) with three quarterly TCD measurements at Weeks 12, 24, and 36; (3) steady-state treatment period (hydroxyurea only or transfusions only) with four quarterly TCD measurements at Weeks 48, 60, 72, and 84; and (4) study exit with three monthly TCD examinations performed at Weeks 96, 100, and 104 or during the accelerated close-out period. The within-patient variance and standard deviation of the TAMV values were found using a linear mixed model, which was calculated using SAS Version 9.3. Results: TAMV measurements on the index side from 1458 TCD examinations on 121 randomized patients formed the overall dataset. TAMV values ≥170 cm/sec were identified in 140 measurements on 40 children (9.6% of TCD values) and exceeded 200 cm/sec in 1.8% of examinations (26 values, 8 children) during the study treatment phase. The within-patient TCD variation, representing fluctuation of repeated TCD measurements in the same study participant, was 12.0 cm/sec for the entire cohort during the initial screening phase (363 TCD measurements). In the initial treatment phase, TCD variation in the hydroxyurea arm (180 values, 60 children) was 10.5 cm/sec, similar to 10.2 cm/sec on the transfusion arm (183 values, 61 children). In the steady-state treatment phase, the TCD variation in the hydroxyurea arm was 10.2 cm/sec (207 values, 57 children), compared to 12.3 cm/sec on the transfusion arm (212 values, 58 children). In the final exit phase, TCD variation in the hydroxyurea arm was 9.8 cm/sec (155 values, 58 children), similar to 10.2 cm/sec on the standard arm (155 values, 57 children). TCD variation was greater with higher baseline TCD velocity and shorter transfusion duration, but was not affected by age or gender. For example, participants with baseline TCD velocity of <170 cm/sec had a post-randomization measurement variation of 10.8 cm/sec, while those ≥170 cm/sec had higher variation (13.7 cm/sec, p=0.001). Conclusions: The TWiTCH trial provides prospective data regarding the biological variation in serial TCD values that occurs in children with previous abnormal TCD examinations but no severe vasculopathy. The observed within-patient variation in TCD velocities was consistently 10-14 cm/sec, with higher variation observed in children with higher baseline TCD velocities. This fluctuation can be expected with serial TCD examinations and should be considered before making treatment decisions based on a single TCD measurement. Since comparison of entry and exit TCD values in the TWiTCH trial documented that hydroxyurea at maximum tolerated dose was non-inferior to transfusions, frequent TCD examinations may not be warranted. Disclosures Ware: Bayer Pharmaceuticals: Consultancy; Addmedica: Research Funding; Global Blood Therapeutics: Consultancy; Bristol Myers Squibb: Research Funding; Biomedomics: Research Funding; Nova Laboratories: Consultancy. Heeney:Eli Lilly and Company: Research Funding; Pfizer: Research Funding; Sancilio and Company: Consultancy, Research Funding. Thompson:Baxalta (now part of Shire): Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mast: Research Funding; Eli Lily: Research Funding; Celgene: Research Funding; Amgen: Research Funding; ApoPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy, Research Funding.
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Delaney, Hannah, Declan Devane, Andrew Hunter, Shaun Treweek, Nicola Mills, Carrol Gamble, and Valerie Smith. "A concept analysis of ‘trial recruitment’ using the hybrid model." HRB Open Research 3 (April 1, 2022): 92. http://dx.doi.org/10.12688/hrbopenres.13173.2.
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Background: The International Committee of Medical Journal Editors (ICMJE) requires trials submitted for publication to be registered before recruitment of the first participant; however, there is ambiguity around the definition of recruitment and in anchoring the trial start date, end date, and recruitment, or as often interchangeably referred to, enrolment, temporally to trial processes. There is potential for variation in how recruitment is reported and understood in trial protocols and trial reports. We report on a concept analysis of ‘trial recruitment’ and develop an operational definition of ‘trial recruitment’. Methods: A concept analysis using the hybrid model. In Phase 1 we examined randomised and non-randomised trial reports (n=150) published between January 2018 and June 2019 to conceptually explore how recruitment was temporally aligned to the four time-points of screening/eligibility, consent, randomisation and allocation. A preliminary operational definition of ‘trial recruitment’ was determined. This definition was further explored, refined and finalised in Phase 2 (field work), through an interactive, discussion-focused workshop with trial recruiters and trial participants. Results: Of the 150 trial reports analysed, over half did not identify a clear time point of when recruitment took place and varying terminology is used when reporting on trial recruitment. In Phase 2, the workshop attendees agreed that the proposed definition of ‘trial recruitment’ offers an acceptable definition that provides a standardised approach of how trial recruitment may be temporally understood as part of overall trial processes. Conclusion: There is ambiguity around temporal descriptions of ‘trial recruitment’ in health care journals. Informed by the findings of this concept analysis we propose a temporal operational definition of trial recruitment based on i) trial recruitment of an individual or cluster and ii) the trial recruitment period.
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Vinci, Giuseppe, Valérie Ventura, Matthew A. Smith, and Robert E. Kass. "Separating Spike Count Correlation from Firing Rate Correlation." Neural Computation 28, no. 5 (May 2016): 849–81. http://dx.doi.org/10.1162/neco_a_00831.
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Populations of cortical neurons exhibit shared fluctuations in spiking activity over time. When measured for a pair of neurons over multiple repetitions of an identical stimulus, this phenomenon emerges as correlated trial-to-trial response variability via spike count correlation (SCC). However, spike counts can be viewed as noisy versions of firing rates, which can vary from trial to trial. From this perspective, the SCC for a pair of neurons becomes a noisy version of the corresponding firing rate correlation (FRC). Furthermore, the magnitude of the SCC is generally smaller than that of the FRC and is likely to be less sensitive to experimental manipulation. We provide statistical methods for disambiguating time-averaged drive from within-trial noise, thereby separating FRC from SCC. We study these methods to document their reliability, and we apply them to neurons recorded in vivo from area V4 in an alert animal. We show how the various effects we describe are reflected in the data: within-trial effects are largely negligible, while attenuation due to trial-to-trial variation dominates and frequently produces comparisons in SCC that, because of noise, do not accurately reflect those based on the underlying FRC.
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Zdenkowski, Nicholas, James F. Lynam, Laura Wall, Scott Brown, Kathryn Wells, and Victoria Sproule. "Breast cancer patients' willingness to travel to participate in a clinical trial." Journal of Clinical Oncology 35, no. 15_suppl (May 20, 2017): e14031-e14031. http://dx.doi.org/10.1200/jco.2017.35.15_suppl.e14031.
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e14031 Background: The option of clinical trial participation is an important component of high quality care for oncology patients. Despite a recognised need for generalizable research results to guide future practice, and the desire of current oncology patients to participate in trials, only 2-5% of oncology patients in developed nations enroll in a clinical trial. We aimed to determine the willingness of patients to travel, change location and/or clinician to participate in a clinical trial. Methods: Members of a national breast cancer consumer organization were invited by email to respond to an online cross-sectional survey. Questions included demographics, remoteness of residence, prior involvement in clinical trials and location of usual care. This was followed by a Discrete Choice Experiment (DCE) comprising an introduction and 10 hypothetical scenarios to test the effect of variation in travel time, clinician, treating centre, travel cost and type of trial. Results: Between July and August 2016, 288 responses were received, mean age 58. 86% had early stage disease, 51% were currently receiving treatment, 21% had prior clinical trial involvement. Ninety percent were willing to participate in a clinical trial in at least one scenario. Factors that decreased the likelihood of interest in clinical trial participation were increasing travel time, change in oncologist and out of pocket expenses. Type of trial (randomised placebo controlled; randomised open label; single arm) did not influence the decision. If the oncologist remained the same and there were no costs, respondents were willing to travel a mean extra 127 minutes, however if the oncologist changed and there were additional costs, they were willing to travel a mean of 30 minutes. If the oncologist changed and there was no cost, they were willing to travel a mean of 82 minutes. Conclusions: This group of respondents with a past history of breast cancer expressed interest in clinical trial participation, however willingness to travel in the most likely scenario (change oncologist and pay no additional cost) was 82 minutes. To facilitate optimal access to clinical trials, clinicians should consider referral within and between institutions.
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Ahmed, Mahbubl, Chee Goh, Edward Saunders, Clara Cieza-Borrella, Zsofia Kote-Jarai, Fredrick R. Schumacher, and Ros Eeles. "Germline genetic variation in prostate susceptibility does not predict outcomes in the chemoprevention trials PCPT and SELECT." Prostate Cancer and Prostatic Diseases 23, no. 2 (November 27, 2019): 333–42. http://dx.doi.org/10.1038/s41391-019-0181-y.
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Abstract Background The development of prostate cancer can be influenced by genetic and environmental factors. Numerous germline SNPs influence prostate cancer susceptibility. The functional pathways in which these SNPs increase prostate cancer susceptibility are unknown. Finasteride is currently not being used routinely as a chemoprevention agent but the long term outcomes of the PCPT trial are awaited. The outcomes of the SELECT trial have not recommended the use of chemoprevention in preventing prostate cancer. This study investigated whether germline risk SNPs could be used to predict outcomes in the PCPT and SELECT trial. Methods Genotyping was performed in European men entered into the PCPT trial (n = 2434) and SELECT (n = 4885). Next generation genotyping was performed using Affymetrix® Eureka™ Genotyping protocols. Logistic regression models were used to test the association of risk scores and the outcomes in the PCPT and SELECT trials. Results Of the 100 SNPs, 98 designed successfully and genotyping was validated for samples genotyped on other platforms. A number of SNPs predicted for aggressive disease in both trials. Men with a higher polygenic score are more likely to develop prostate cancer in both trials, but the score did not predict for other outcomes in the trial. Conclusion Men with a higher polygenic risk score are more likely to develop prostate cancer. There were no interactions of these germline risk SNPs and the chemoprevention agents in the SELECT and PCPT trials.
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Dal-Ré, Rafael, Ben Goldacre, Ignacio Mahillo-Fernández, and Nicholas J. DeVito. "European non-commercial sponsors showed substantial variation in results reporting to the EU trial registry." Journal of Clinical Epidemiology 142 (February 2022): 161–70. http://dx.doi.org/10.1016/j.jclinepi.2021.11.005.
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Stair, Thomas O., Caitlin R. Reed, Michael S. Radeos, Greg Koski, and Carlos A. Camargo. "Variation in Institutional Review Board Responses to a Standard Protocol for a Multicenter Clinical Trial." Academic Emergency Medicine 8, no. 6 (June 2001): 636–41. http://dx.doi.org/10.1111/j.1553-2712.2001.tb00177.x.
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Jones, Marcus, Marin Harbur, and Ken J. Moore. "Automating Uniformity Trials to Optimize Precision of Agronomic Field Trials." Agronomy 11, no. 6 (June 21, 2021): 1254. http://dx.doi.org/10.3390/agronomy11061254.
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Plot size has an important impact on variation among plots in agronomic field trials, but is rarely considered during the design process. Uniformity trials can inform a researcher about underlying variance, but are seldom used due to their laborious nature. The objective of this research was to describe variation in maize field trials among field plots of varying size and develop a tool to optimize field-trial design using uniformity-trial statistics. Six uniformity trials were conducted in 2015–2016 in conjunction with Iowa State University and WinField United. All six uniformity trials exhibited a negative asymptotic relationship between variance and plot size. Variance per unit area was reduced over 50% with plots 41.8 m2 in size and over 75% when using a plot size >111.5 m2 compared to a 13.9 m2 plot. Plot shape within a fixed plot size did not influence variance. The data illustrated fewer replicates were needed as plot size increased, since larger plots reduced variability. Use of a Shiny web application is demonstrated that allows a researcher to upload a yield map and consider uniformity-trial statistics to inform plot size and replicate decisions.
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Coyle, Douglas, and Michael F. Drummond. "ANALYZING DIFFERENCES IN THE COSTS OF TREATMENT ACROSS CENTERS WITHIN ECONOMIC EVALUATIONS." International Journal of Technology Assessment in Health Care 17, no. 2 (April 2001): 155–63. http://dx.doi.org/10.1017/s0266462301105015.
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Objectives: Assessments of health technologies increasingly include economic evaluations conducted alongside clinical trials. One particular concern with economic evaluations conducted alongside clinical trials is the generalizability of results from one setting to another. Much of the focus relating to this topic has been on the generalizability of results between countries. However, the characteristics of clinical trial design require further consideration of the generalizability of cost data between centers within a single country, which could be important in decisions about adoption of the new technology.Methods: We used data from a multicenter clinical trial conducted in the United Kingdom to assess the degree of variation in costs between patients and between treatment centers and the determinants of the degree of such variation.Results: The variation between patients was statistically significant for both the experimental and conventional treatments. However, the degree of variation between centers was only statistically significant for the experimental treatment. Such variation appeared to be a result of hospital practice, such as payment mechanisms for staff and provision of hostel accommodation, rather than variations in physical resource use or substantive differences in cost structure.Conclusions: Multicenter economic evaluations are necessary for determining the variations in hospital practice and characteristics that can in turn determine the generalizability of study results to other settings. Such analyses can identify issues that may be important in adopting a new health technology. Analysis is required of similar large multicenter trials to confirm these conclusions.
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Nantongo, Judith S., Brad M. Potts, Hugh Fitzgerald, Jessica Newman, Stephen Elms, Don Aurik, Heidi Dungey, and Julianne M. O’Reilly-Wapstra. "Quantitative Genetic Variation in Bark Stripping of Pinus radiata." Forests 11, no. 12 (December 18, 2020): 1356. http://dx.doi.org/10.3390/f11121356.
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Bark stripping by mammals is a major problem for conifer forestry worldwide. In Australia, bark stripping in the exotic plantations of Pinus radiata is mainly caused by native marsupials. As a sustainable management option, we explored the extent to which natural variation in the susceptibility of P. radiata is under genetic control and is thus amenable to genetic improvement. Bark stripping was assessed at ages four and five years in two sister trials comprising 101 and 138 open-pollinated half-sib families. A third younger trial comprising 74 full-sib control-pollinated families was assessed at two and three years after planting. Significant additive genetic variation in bark stripping was demonstrated in all trials, with narrow-sense heritability estimates between 0.06 and 0.14. Within sites, the amount of additive genetic variation detected increased with the level of bark stripping. When strongly expressed across the two sister trials, the genetic signal was stable (i.e., there was little genotype × environment interaction). No significant non-additive effect (specific combining ability effect) on bark stripping was detected in the full-sib family trial, where it was estimated that up to 22.1% reduction in bark stripping might be achieved by selecting 20% of the less susceptible families. Physical traits that were genetically correlated, and likely influenced the amount of bark removed from the trees by the marsupials, appeared to depend upon tree age. In the older trials, these traits included bark features (presence of rough bark, rough bark height, and bark thickness), whereas in the younger trial where rough bark was not developed, it was the presence of obstructive branches or needles on the stem. In the younger trial, a positive genetic correlation between prior height and bark stripping was detected, suggesting that initially faster growing trees exhibit more bark stripping than slower growing trees but later develop rough bark faster and became less susceptible. While the presence of unexplained genetic variation after accounting for these physical factors suggests that other explanatory plant traits may be involved, such as chemical traits, overall the results indicate that selection for reduced susceptibility is possible, with potential genetic gains for deployment and breeding.
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Schoenfeld, David Alan, Dianne M. Finkelstein, Eric Macklin, Neta Zach, David L. Ennist, Albert A. Taylor, and Nazem Atassi. "Design and analysis of a clinical trial using previous trials as historical control." Clinical Trials 16, no. 5 (July 1, 2019): 531–38. http://dx.doi.org/10.1177/1740774519858914.
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Background/AimsFor single arm trials, a treatment is evaluated by comparing an outcome estimate to historically reported outcome estimates. Such a historically controlled trial is often analyzed as if the estimates from previous trials were known without variation and there is no trial-to-trial variation in their estimands. We develop a test of treatment efficacy and sample size calculation for historically controlled trials that considers these sources of variation.MethodsWe fit a Bayesian hierarchical model, providing a sample from the posterior predictive distribution of the outcome estimand of a new trial, which, along with the standard error of the estimate, can be used to calculate the probability that the estimate exceeds a threshold. We then calculate criteria for statistical significance as a function of the standard error of the new trial and calculate sample size as a function of difference to be detected. We apply these methods to clinical trials for amyotrophic lateral sclerosis using data from the placebo groups of 16 trials.ResultsWe find that when attempting to detect the small to moderate effect sizes usually assumed in amyotrophic lateral sclerosis clinical trials, historically controlled trials would require a greater total number of patients than concurrently controlled trials, and only when an effect size is extraordinarily large is a historically controlled trial a reasonable alternative. We also show that utilizing patient level data for the prognostic covariates can reduce the sample size required for a historically controlled trial.ConclusionThis article quantifies when historically controlled trials would not provide any sample size advantage, despite dispensing with a control group.
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Shi, Yang, and Ji-Hyun Lee. "Sample size calculations for group randomized trials with unequal group sizes through Monte Carlo simulations." Statistical Methods in Medical Research 27, no. 9 (December 15, 2016): 2569–80. http://dx.doi.org/10.1177/0962280216682775.
Full textAbstract:
Group randomized trial design is common in cancer prevention and health promotion research with intervention development. Several methods have been developed to handle the design and analytical issues for group randomized trial including the intraclass correlation coefficient. The widely used methods for the sample size calculation for the group randomized trial assume equal sizes across groups. In practice this assumption often fails and group randomized trial studies suffer from considerably lower statistical power than as planned. A few studies have developed sample size calculation methods for unequal group sizes, but most of them are limited to continuous outcomes. In this study, we develop a method for sample size calculation for group randomized trial studies with unequal group sizes based on Monte Carlo simulation in the mixed effect model framework. This approach incorporates the variation of group sizes and can be applied to group randomized trials with different types of outcomes. Further, it is easy to implement and can be applied to most commonly used group randomized trial designs such as pre-and-post cross-sectional and cohort study designs. We demonstrate the application of the proposed approach to two-arm group randomized trial studies with continuous and binary outcomes through simulations and analysis of a real group randomized trial dataset.
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Warwick, S. I., R. K. Gugel, C. Gómez-Campo, and T. James. "Genetic variation in Eruca vesicaria (L.) Cav." Plant Genetic Resources: Characterization and Utilization 5, no. 03 (November 22, 2007): 142–53. http://dx.doi.org/10.1017/s1479262107842675.
Full textAbstract:
Eruca vesicariasubsp.sativa(syn.E. sativa) is a cruciferous vegetable and oilseed crop that is high in erucic acid. It occurs throughout the Mediterranean region and western Asia, and has been naturalized elsewhere as a crop/weed escape. It is closely related to subsp.vesicariaand subsp.pinnatifida, which are endemic to Spain and north-western Africa, respectively. This study evaluated patterns and levels of diversity in the three subspecies based on 234 amplified fragment length polymorphisms (AFLP), and evaluated agronomic and seed quality data in a field trial in western Canada. AFLP data revealed three main clusters: ‘Sativa’ (33 accessions of subsp.sativa), ‘Vesicaria’ (nine accessions of subsp.vesicaria) and a ‘Pinnatifida’ cluster (one accession of subsp.pinnatifidaand three Moroccan accessions of subsp.sativa). The Sativa cluster separated into Mediterranean and Asian groups, likely reflecting differences in origin (wild versus cultivated) or primary usage, vegetable versus seed oil. The origin of the introduced Mexican population was confirmed as subsp.sativa. The highest levels of diversity were found in the Sativa cluster (88% AFLP polymorphisms) and the least in the Vesicaria (56%) and Pinnatifida (39%) clusters. Extensive variation was observed among the 159 subsp.sativaaccessions evaluated in the field trial, and overall findings indicated a favourable agronomic potential.
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Steinvorth, Simon M., Christian Röver, Simon Schneider, Richard Nicholas, Sebastian Straube, and Tim Friede. "Explaining temporal trends in annualised relapse rates in placebo groups of randomised controlled trials in relapsing multiple sclerosis: systematic review and meta-regression." Multiple Sclerosis Journal 19, no. 12 (March 7, 2013): 1580–86. http://dx.doi.org/10.1177/1352458513481009.
Full textAbstract:
Background: Recent studies have shown a decrease in annualised relapse rates (ARRs) in placebo groups of randomised controlled trials (RCTs) in relapsing multiple sclerosis (RMS). Methods: We conducted a systematic literature search of RCTs in RMS. Data on eligibility criteria and baseline characteristics were extracted and tested for significant trends over time. A meta-regression was conducted to estimate their contribution to the decrease of trial ARRs over time. Results: We identified 56 studies. Patient age at baseline ( p < 0.001), mean duration of multiple sclerosis (MS) at baseline ( p = 0.048), size of treatment groups ( p = 0.003), Oxford Quality Scale scores ( p = 0.021), and the number of eligibility criteria ( p<0.001) increased significantly, whereas pre-trial ARR ( p = 0.001), the time span over which pre-trial ARR was calculated ( p < 0.001), and the duration of placebo-controlled follow-up ( p = 0.006) decreased significantly over time. In meta-regression of trial placebo ARR, the temporal trend was found to be insignificant, with major factors explaining the variation: pre-trial ARR, the number of years used to calculate pre-trial ARR and study duration. Conclusion: The observed decline in trial ARRs may result from decreasing pre-trial ARRs and a shorter time period over which pre-trial ARRs were calculated. Increasing patient age and duration of illness may also contribute.