Proponents of privately run prisons contend that cost-savings and efficiency of operation place private prisons at an advantage over public prisons and support the argument for privatization, but some research casts doubt on the validity of these arguments, as evidence has shown that private prisons are neither demonstrably more cost-effective, nor more efficient than public prisons.[20] An evaluation of 24 different studies on cost-effectiveness revealed that, at best, results of the question are inconclusive and, at worst, there is no difference in cost-effectiveness.[53]