I am running a mixed ANOVA in SPSS with 1 between subjects factor (4 levels of group) and 1 within subject factor (7 levels). The distribution of race is significantly different between my groups and I would like to control for that. Race is coded as 0=African American, 1=Caucasian, 2=Asian, 4=Native American, etc. In SPSS, can I just put the categorical variable race into the covariate box in a repeated measures ANOVA? Or do I need to do some sort of coding? The race variable is labeled as a "nominal" measure, so SPSS should know that it's not continuous variable.