“A Peculiar Prevalence of p Values Just below 0.05”, 2012-11-01 (; backlinks; similar):
In null hypothesis statistical-significance testing (NHST), p-values are judged relative to an arbitrary threshold for statistical-significance (0.05). The present work examined whether that standard influences the distribution of p-values reported in the psychology literature.
We examined a large subset of papers from 3 highly regarded journals. Distributions of p were found to be similar across the different journals. Moreover, p-values were much more common immediately below 0.05 than would be expected based on the number of p-values occurring in other ranges. This prevalence of p-values just below the arbitrary criterion for statistical-significance was observed in all 3 journals.
We discuss potential sources of this pattern, including publication bias and researcher degrees of freedom.