نتایج جستجو برای: sample size calculation

تعداد نتایج: 994380  

Journal: :Biometrics 2004
Wesley O Johnson Chun-Lung Su Ian A Gardner Ronald Christensen

We develop a Bayesian approach to sample size computations for surveys designed to provide evidence of freedom from a disease or from an infectious agent. A population is considered "disease-free" when the prevalence or probability of disease is less than some threshold value. Prior distributions are specified for diagnostic test sensitivity and specificity and we test the null hypothesis that ...

2017
Caroline Kristunas Tom Morris Laura Gray

OBJECTIVES To investigate the extent to which cluster sizes vary in stepped-wedge cluster randomised trials (SW-CRT) and whether any variability is accounted for during the sample size calculation and analysis of these trials. SETTING Any, not limited to healthcare settings. PARTICIPANTS Any taking part in an SW-CRT published up to March 2016. PRIMARY AND SECONDARY OUTCOME MEASURES The pr...

2017
Humam Saltaji Susan Armijo-Olivo Greta G Cummings Maryam Amin Carlos Flores-Mir

OBJECTIVES To examine the risks of bias, risks of random errors, reporting quality, and methodological quality of randomized clinical trials of oral health interventions and the development of these aspects over time. METHODS We included 540 randomized clinical trials from 64 selected systematic reviews. We extracted, in duplicate, details from each of the selected randomized clinical trials ...

Journal: :Indian Journal of Anaesthesia 2016

Journal: :Indian Journal of Ophthalmology 2010

2010
Nithya J Gogtay

In most areas in life, it is difficult to work with populations and hence researchers work with samples. The calculation of the sample size needed depends on the data type and distribution. Elements include consideration of the alpha error, beta error, clinically meaningful difference, and the variability or standard deviation. The final number arrived at should be increased to include a safety...

2016
Sabyasachi Das Koel Mitra Mohanchandra Mandal

Addressing a sample size is a practical issue that has to be solved during planning and designing stage of the study. The aim of any clinical research is to detect the actual difference between two groups (power) and to provide an estimate of the difference with a reasonable accuracy (precision). Hence, researchers should do a priori estimate of sample size well ahead, before conducting the stu...

Journal: :iranian endodontic journal 0
arash shahravan ali-akbar haghdoost maryam rad maryamalsadat hashemipoor maryam sharifi

introduction: the purpose of this article was to evaluate the quality of sample size calculation reports in published clinical trials in journal of endodontics and international endodontic journal in years 2000-1 and 2009-10. materials and methods: articles fulfilling the inclusion criteria were collected. the criteria were: publication year, research design, types of control group, reporting s...

Journal: :Deutsches Aerzteblatt Online 2010

Journal: :The Stata Journal: Promoting communications on statistics and Stata 2013

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