Globally, at least 11 million people are held in prisons and other penal institutions, a number which has increased by more than 10 percent over the past decade. Prisoners often come from marginalized groups in society with limited economic opportunities, and children in prison are mostly those...

In the data, a sizable fraction of price changes are temporary price reductions referred to as sales. Existing models include no role for sales. Hence, when confronted with data in which a large fraction of price changes are sales related, the models must either exclude sales from the data or...