Given a set of dichotomously scored items, ordering theory attempts to identify a hierarchy among those items. A graphic representation is presented for an empirically obtained hierarchy and a testing procedure to evaluate hypothesized hierarchical relationships. (Author/JKS)

Research on 128 children is presented as evidence of the superiority of a new clustering measure (X) over a more traditional "chance clustering" measure (sigma) as a means of organizing material to be learned to facilitate recall. X is shown to meet three criteria for a measure of a developmental process: X is more highly correlated with recall…