Sources of Artifacts in SLODR Detection.

Background: Spearman's law of diminishing returns (SLODR) states that intercorrelations between scores on tests of intellectual abilities were higher when the data set was comprised of subjects with lower intellectual abilities and vice versa. After almost a hundred years of research, this trend has only been detected on average.

Objective: To determine whether the very different results were obtained due to variations in scaling and the selection of subjects.