I wonder if it is correct to conduct a mediation test in the following case:
1) Independent variable is anxiety score measured at time 1
2) Dependent variable is cocaine consumption measured at time 2
3) Mediator variable would be anxiety score measured at time 2.
Would a "classical" mediation model be correct (apart from the problem that the outcome is binary whereas the mediator would be continuous)? Or the fact that the independent variable and the mediator are the same (although measured at two different times) precludes this analysis?