I am assessing the relationship between ritual killing ((outcome variable) and state location of killer (predictor variable #1) and race of killer (predictor variable #2) using 2-way ANOVA with my data imported from Excel. I have secondary data for the outcome variable and the 2 predictors. I want to adjust for confounders, such as alcohol use, drug use, depression, and poverty but no data for these. What are the steps to adjust for these confounders although I don't have secondary or primary data on them using SPSS?