BACKGROUND The objective of this work was the study of analogical reasoning from the perspective of the equivalence-equivalence phenomenon. METHOD The variables studied consisted of the age of the participants and the educational level of the parents, in relation to performance on a reasoning task. The task utilized a sample size of 64 participants and an instrument based on conditional discr...

The scientific community's reliance on active-controlled trials is steadily increasing, as widespread agreement emerges concerning the role of these trials as viable alternatives to placebo trials. These trials present substantial challenges with regard to design and interpretation as their complexity increases, and the potential need for larger sample sizes impacts the cost and time variables ...

Noncompliance with study medications is an important issue in the design of endpoint clinical trials. Including noncompliant patient data in an intention-to-treat analysis could seriously decrease study power. Standard methods for calculating sample size account for noncompliance, but all assume that noncompliance is noninformative, i.e., that the risk of discontinuation is independent of the r...

Mediation models are widely used, and there are many tests of the mediated effect. One of the most common questions that researchers have when planning mediation studies is, "How many subjects do I need to achieve adequate power when testing for mediation?" This article presents the necessary sample sizes for six of the most common and the most recommended tests of mediation for various combina...

Our think tank tasked by the Dutch Health Council, consisting of Radboud University Nijmegen Honours Academy students with various backgrounds, investigated the implications of Deep Brain Stimulation (DBS) for psychiatric patients. During this investigation, a number of methodological, ethical and societal difficulties were identified. We consider these difficulties to be a reflection of a stil...

Utilizing a multicenter approach in observational clinical research allows for improved generalizability of the results, a larger sample size, and, consequently, improved efficiency. This paper highlights important issues with regard to the organization of multicenter observational studies in orthopaedic research. Specifically, we emphasize the development of trial committees, stress the import...

This note investigates the adequacy of the finite sample approximation provided the Functional Central Limit Theorem when the errors are allowed to be dependent. We compare the distribution of the scaled partial sums of some data with the distribution of the Wiener process to which it converges. Our setup is, on purpose, very simple in that it considers data generated from an ARMA(1,1) process....

Power calculations are derived for matched case-control studies in terms of the probability po of exposure among the control patients, the correlation coefficient phi for exposure between matched case and control patients, and the odds ratio psi for exposure in case and control patients. For given Type I and Type II error probabilities alpha and beta, the odds ratio that can be detected with a ...

Statistical power and thus the sample size required to achieve some desired level of power depend on the size of the effect of interest. However, effect sizes are seldom known exactly in psychological research. Instead, researchers often possess an estimate of an effect size as well as a measure of its uncertainty (e.g., a standard error or confidence interval). Previous proposals for planning ...

Our answer to the question posed in the title is negative. This intentionally provocative note discusses the issue of sample size in microarray studies from several angles. We suggest that the current view of microarrays as no more than a screening tool be changed and small sample studies no longer be considered appropriate.