This is a mixed model, not a purely random effects model.

Would anything purely random, like a short circuit, repeat similar patterns two nights in succession?

We are born by accident into a purely random universe.

Many of those might give on empty interstellar space, as a purely random course around the cylinder most certainly would.

Mathematicians do not really know what "purely random" means.

A universe of purely random events would be no universe at all.

Most believe that the original origin of chiralities was purely random.

Maybe that's because I cannot accept that the human brain ever operates in a purely random manner.

She understood her father's point that his personal conversation with Sanchez was purely random.

No, because the connection between those two numbers is purely random.