Statistical Power, Sampling, and Effect Sizes

This article discusses the interrelated issues of statistical power, sampling, and effect sizes when conducting rigorous quantitative research. Technical and practical connections are made between these concepts and various inferential tests. To increase power and generate effect sizes that merit practical or clinical notice, not only must the research aims and associated design be well devised, reflecting best scientific practice, state of the art sampling procedures should be applied with sufficiently large and representative number of participants. Applications to research conducted in the counseling profession are included.