The Prevalence of Marginally Significant Results in Psychology Over Time

We examined the percentage of p values (.05 < p ≤ .10) reported as marginally significant in 44,200 articles, across nine psychology disciplines, published in 70 journals belonging to the American Psychological Association between 1985 and 2016. Using regular expressions, we extracted 42,504 p values between .05 and .10. Almost 40% of p values in this range were reported as marginally significant, although there were considerable differences between disciplines. The practice is most common in organizational psychology (45.4%) and least common in clinical psychology (30.1%). Contrary to what was reported by previous researchers, our results showed no evidence of an increasing trend in any discipline; in all disciplines, the percentage of p values reported as marginally significant was decreasing or constant over time. We recommend against reporting these results as marginally significant because of the low evidential value of p values between .05 and .10.

Marginally Significant Effects as Evidence for Hypotheses: Changing Attitudes Over Four Decades

Some effects are statistically significant. Other effects do not reach the threshold of statistical significance and are sometimes described as "marginally significant" or as "approaching significance." Although the concept of marginal significance is widely deployed in academic psychology, there has been very little systematic examination of psychologists' attitudes toward these effects. Here, we report an observational study in which we investigated psychologists' attitudes concerning marginal significance by examining their language in over 1,500 articles published in top-tier cognitive, developmental, and social psychology journals. We observed a large change over the course of four decades in psychologists' tendency to describe a p value as marginally significant, and overall rates of use appear to differ across subfields. We discuss possible explanations for these findings, as well as their implications for psychological research.