The indicators used for a set of taxometric analyses should demonstrate at least 1.25 standard deviation units (SDU) of separation between the presumptive taxon and complement groups (Meehl, 1995). In the SECCYD sample, 94 (9.7%) of the children met the DSM-IV-TR criteria for ODD based on the mother and teacher responses to the DBQ, which is within the range of prevalence rates of ODD in the general population (1 to 11%; APA, 2013; Canino et al., 2010)—and is generally consistent with an estimate in the United States based on a structured diagnostic interview (7.1%; Canino et al., 2010). Using these case classifications, the eight DBQ items had excellent indicator validity (Table 1, which also includes the average correlations among the eight indicators in the full sample, the putative taxon group, and the putative complement group). Alternatively, when the MAMBAC and MAXEIG procedures were used to generate a base rate estimate, this average estimate of 19% also yielded strong indicator coefficients (Table 1). Each set of taxometric analyses was run twice, first using simulated taxonic data derived from the diagnostic classifications
