I'm trying to see how latency to emerge (response variable) is varies with time (trials). Individuals (ID) are nested within colonies. The nesting is such that individuals 1-20 belong to colony 1, 21-40 to colony 2, and so on. I would like to see how latency of individuals vary with time by fitting a random slope model, and at the same time accounting for the non-independence of individuals from colonies. I'm confused which is the correct formula because the outputs are different:
m1 gives interactions of all individuals with trials. However, output of
m2 says "singular fit".