I got a data set and codes as follows to estimate a variance component. In the data set "y" is the response, "fuel" has fixed and "day" has random effects in the linear mixed model. I can estimate random effect due to "day" and there is no option to have a p-value corresponding to the estimate of random effect. How can I estimate the p-value? Is there any other package for that? Any answer would be appreciated much.

day