Diminishing returns as a function of the association between within-individual average performance and variance

It has been demonstrated that the worst performance rule (WPR) effect can occur as a result of statistical dependencies in data. Here, we examine whether this might also be case for Spearman's law diminishing returns (SLODR). Two proposed SLODR criteria are skewness estimated latent ability factor and correlation between within-individual residual variance. Using four publicly available datasets, covering quite different dimensions behavior, show both these affected by average variance on test scores. However, influence two goes opposite directions, which suggests it generally difficult to get results unambiguously support SLODR. These have far-reaching implications literature, extent various research findings attributed human cognitive functioning fact due trivial This is an important issue address future research.