I am currently doing an ANCOVA with :
- dependent variable : volume of the right hippocampus
- IV (factor) : group (with 2 dimensions)
- IV (factor): timepoint (with 2 dimensions)
- 2 covariates : age and tiv (total intracranial volume)
I tried first to do it with 1 covariate. When I want to add a 2nd covariate, it doesn't always work.
res.aov1 <- df1 %>%
anova_test(rHip ~ age + tiv + group*timepoint)
#significative effects of age, tiv and group
pwc <- df1 %>%
rHip ~ group, covariate = age,
p.adjust.method = "bonferroni"
pwc %>% filter(timepoint == "t1")
----> How can I add a 2nd covariate to this last part ?
Or if someone can give me an example of any ANCOVA with 2 covariates that would help me a lot.