Sample Size in Psychological Research

Abstract

This study was conducted to provide information on the typical sample size employed in psychological research, as it is reported in selected American Psychological Association journals. All the articles in those journals for the years 1955 and 1977 were read to ascertain both the total n for the study, and the size of each of the groups that made up that total n. The mean, SD, median, 25th percentile, 75th percentile, modes, and range were calculated for each year, both for total n and for individual group n. A comparison of the 1955 data and the 1977 data showed no significant changes in sample size between those years. Certain problems in determining sample size, as it was reported, are presented in this article.