cross-level interaction with Level-1 moderator
Posted: Fri Sep 25, 2015 1:03 pm
We have a three-level model with time-of-day (binary: morning versus afternoon, Level 1) nested in days (Level 2) nested in persons (Level 3). We want to test a cross-level interaction with the Level-1 variable moderating the relationship between a Level-2 predictor variable and the Level-1 outcome variable. Note: this cross-level interaction is different from the "usual" cross-level interaction where the Level-2 variable is the moderator.
In MLwiN we can build an interaction term between the Level-2 predictor and the Level-1 moderator, this is straightforward. But we are wondering how we should treat fixed versus random slopes: in our model the effect from the Level-2 predictor variable on the Level-1 outcome is contingent on the score of the Level-1 moderator. Thus, would it make sense to specify a random slope of the Level-2 predictor (i.e., the slope varying at Level 1)? It is possible in technical terms, but appears strange within the multilevel logic.
In MLwiN we can build an interaction term between the Level-2 predictor and the Level-1 moderator, this is straightforward. But we are wondering how we should treat fixed versus random slopes: in our model the effect from the Level-2 predictor variable on the Level-1 outcome is contingent on the score of the Level-1 moderator. Thus, would it make sense to specify a random slope of the Level-2 predictor (i.e., the slope varying at Level 1)? It is possible in technical terms, but appears strange within the multilevel logic.