I ran a two-way between subjects ANCOVA with drug (2 levels-drug and no drug) and groups (depressed, confused and normal) as the IVs and the number of errors on a cognitive task as the DV. I included age as the covariate in my ANCOVA and it turns out to be highly significant (p < 0.001) and has the largest effect size. Groups were not age matched in any way, samples were equal across the three groups and 2 drug conditions, the design is between subjects and all assumptions for ANCOVA were met. I was wondering how I can follow up this significant effect of the covariate. I ran a correlation and it turns out the covariate is highly significant with the DV. What can I do to further explore the relationship between the two?