Paul R. Yarnold

Optimal Data Analysis, LLC

Mean scores on a continuous dependent measure are compared across three or more groups using one-way analysis of variance (ANOVA). If a statistically significant overall or “omnibus” effect emerges, then a multiple comparisons procedure is used to ascertain the exact nature of any interclass differences. In contrast, the dependent measure may be compared between classes with UniODA to assess if thresholds on the dependent measure can discriminate the classes. If the resulting ESS accuracy statistic for the overall effect is statistically reliable then an optimal (maximum-accuracy) range test is employed to ascertain the exact nature of interclass differences. ANOVA and UniODA are used to investigate the differences between *n*=377 white, *n*=378 African American, and *n*=257 Hispanic patients with HIV-associated *Pneumocystis carinii* pneumonia (PCP) on two laboratory tests (albumin and alveolar-arterial oxygen difference) associated with PCP outcomes.