View Full Version : Statistical Power and Sample Size

03-17-2009, 04:10 AM
Dear Readers,

I am hoping that some of you who have expertise in the area of statistics and scientific journal review can help me with the following concern.

Recently I have submitted papers to peer-review journals that describe the results of investigations performed on 'small sample sizes'. Obviously, small is a relative term. For the sake of this discussion, my samples sizes have been greater than 4 and less than 10 persons.

Multiple times I have received reviewer comments that the sample size was too small, which limited my results. What concerns me is that most of my investigations involve a repeated measures design, during which subjects are tested in two or three environments, with the objective being to determine the affect the environment has on my measure. I typically use a paired t-test or repeated measures ANOVA with a post hoc evaluation if a significant main effect is determined.

In these papers, if I were to fail to reject the null hypothesis, then I can understand the concern about power and sample size. However, in many of my papers, I have determined a significant effect relative to an a priori p