Consider the model:
mrdrdtit = ηt + β1execit + β2unempit + ai + uit
where ηt denotes different year intercepts (i.e., a set of year dummy variables), and ai is an unobserved effect for state i. If past executions of convicted murderers deter people from murdering, what should be the sign of β1? What sign do you expect β2 to have? Why?