I have a data like this, ticks feed on three groups of treated mouses, compare whether the treatment has an effect on ticks' bacteria load.
when I made a mixed model like:
lmer.model01 = lmer(log10.load ~ treat + (1|mouse.id/tick.id))
The screen says:
Error: number of levels of each grouping factor must be < number of observations
What happened and how can I change my model?