I know there have been a number of posts on lmer, but I am struggling to find my answer through research and am hoping to get your help.
I am analyzing data from a study with the following data:
1) Score = the DV, a participants score on a given test.
2) Test = IV, within-subjects variable. Tests were taken at 4 different time points--1 pre intervention and 3 post intervention tests. Not all participants completed all 4 tests.
3) Group = between-subjects variable, subjects were assigned to either an intervention or control group.
4) Resistance = a covariate that may explain why intervention was more/less effective in a given participant.
I want to know whether Score varies as a function of Group across tests. I'd also like to know whether Resistance modifies the change in test scores moreso for the intervention group than the control (so, a three way interaction, I think?).
Seriously, any help, advice, links to resources would be incredibly useful.