What does this warning means? Should I change the code? And how?

[mitzimorris]

see Ben’s answer here:

Metropolis proposal rejected because location parameter is infinite

Hi! I’m new to Stan, and I’m trying to build a fairly simple model of people’s performances on crosswords. The data is a set of records with a crossword time, which crossword it was, and which user solved the crossword. The model estimates log-seconds by adding a constant, a per-user effect, and a per-crossword effect. The current Stan code can be found here. (It contains some extra effects but they are minor.) When I train my model, during the warm-up phase only, I get several messages like t…