The use of effect size estimates in planning the sample size necessary for a future study can introduce substantial bias in the sample size planning process. For instance, the uncertainty associated with the effect size estimate may result in average statistical power that is substantially lower than the nominal power specified in the calculation. The present manuscript examines methods for inc...

PURPOSE This pilot study examines the effects of walking a labyrinth. METHOD A convenience sample of 25 community members participated in a four-group, repeated measures study to gather information about vital signs and affect before and after labyrinth walks. Because of the small sample size, results were inspected for effect size (ES) differences in pre-to postcomparisons. Mean postwalk sco...

In the present article, we investigate predictors of how often a scientific article is cited. Specifically, we focus on the influence of two often neglected predictors of citation rate: effect size and sample size, using samples from two psychological topical areas. Both can be considered as indicators of the importance of an article and post hoc (or observed) statistical power, and should, esp...

Sample-size determination is often an important step in planning an epidemiological study. There are several approaches to determining sample size. It depends on the type of the study. Descriptive, observational and randomized controlled studies have different formulas to calculate sample size. In this article, we discuss the formulas that can help to estimate sample size in an epidemiological ...

An appropriate sample size is crucial for the success of many studies that involve a large number of comparisons. Sample size formulas for testing multiple hypotheses are provided in this paper. They can be used to determine the sample sizes required to provide adequate power while controlling familywise error rate or false discovery rate, to derive the growth rate of sample size with respect t...

The eeect of noise in a dichotomous process is studied from the Bayesian viewpoint. Winkler's approximation to the posterior distribution in the presence of noise is shown to break down badly near the limits of its application. Information loss is measured using eeective sample size. An account of the relationship between eeective sample size/information loss and sampling data is given which di...