Using the nlme package in R, I ran a multilevel regression model model with a random intercept and a fixed linear effect of time with REML estimation:
lme(fixed = outcome ~ 1 + day, random = ~ 1 | ID, data = data, method = "REML", na.action = na.exclude)
The p-values for the fixed effects are exactly 0 - not 0.0000 as I've seen before. Does this indicate that something is wrong with my model?