Objectives

The aim of this article is to outline how certain key assumptions affect the quality and interpretation of research in quantitative sport and exercise psychology.

Methods

A review of three common assumptions made in the sport and exercise psychology literature was conducted. The review focused on three assumptions relating to research validity and the treatment and interpretation of observations. A central theme to this discussion is the assumption that research observations reflect true effects in a population.

Results

Assumptions often made in sport and exercise psychology research were identified in three key areas: (1) validity, (2) inferences of causality, and (3) effect size and the “practical significance” of research findings. Findings indicated that many studies made assumptions about the validity of the self-report psychological measures adopted and few provided a comprehensive evaluation of the validity of these measures. Researchers adopting correlational designs in sport and exercise psychology often infer causality despite such conclusions being based on theory or speculation rather than empirical evidence. Research reports still do not include effect size statistics as standard and confine the discussion of findings to statistical significance alone rather than commenting on “practical significance”.

Conclusion

Research quality can only be evaluated with due consideration of the common assumptions that limits empirical investigation in sport and exercise psychology. We offer some practical advice for researchers, reviewers, and journal editors to minimise the impact of these assumptions and enhance the quality of research findings in sport and exercise psychology.