Sample sizes in sport and exercise psychology: Have they increased in the past decade?

Although the past decade was characterized by methodological discussions regarding the quality of psychological research, there is sparse empirical evidence whether research practices have changed since the beginning of the debate. We aim to investigate whether sample sizes in sport and exercise psychology have increased in the past decade. We analyze four leading journals in sport and exercise psychology regarding sample sizes of all quantitative studies published in these journals between 2022 and 2023. Then we compare these sample sizes to the sample sizes published in the same journals between 2009 and 2013 (Schweizer & Furley, 2016). Our results suggest that sample sizes in sport and exercise psychology have increased for most, but not all study designs (e.g., median sample sizes increased by 44% and 33% for experimental and correlational studies, whereas they decreased by 25% for quasi-experimental studies). Although power may have increased accordingly, our results suggest that a substantial proportion of studies in sport and exercise psychology may still not have sufficient power to detect small-to-medium effects, particularly so when testing at low alpha levels. More than half of the studies in our sample do not report an a priori power analysis, and a priori power analyses are not uniformly related to sample sizes across study designs. Taken together, the present study suggests that sample sizes in sport and exercise psychology have increased in the past decade. However, there is still room for improvement. In order to remedy this shortcoming, we suggest investing in training how to perform a priori power analyses and in creating applications that make it easier to conduct respective power analyses.