The convergent validity of MMPI and Rorschach scales: an extension using profile scores to define response and character styles on both methods and a reexamination of simple Rorschach response frequency
Past research indicated the convergence of Rorschach and MMPI scales may be a function of (a) simple Rorschach response frequency (R) or (b) complex response-character styles on both methods. In this study, new criteria were developed for defining the second assumption using F and K from the MMPI and R and Lambda from the Rorschach. Although substantially different from the factor criteria used previously (KS = .45 and .30), the new criteria still produced the expected pattern of correlations among MMPI and Rorschach scales. Averaged across 17 constructs, the new criteria produced strong validity coefficients for patients with similar styles (M composite r = .50), though they were less effective for patients with discordant styles (M composite r = -.27). It was also demonstrated that R by itself does not moderate convergent validity. Rather, statistical modeling with two sets of 300 random samples (a) demonstrated the prior findings related to R were the result of sampling error and (b) supported the general hypothesis that Rorschach and MMPI scales correlate to the extent response-character styles correlate. Implications are considered.