But critics, such as Valerie Ramey of the University of California at San Diego, think that Guajardo, Leigh, and Pescatori have not completely proven their case. It is possible, Ramey argues, that their results could reflect a different sort of reverse causality if governments are more likely to respond to high public-debt levels with austerity programs when they have reason to believe that economic conditions could make the debt burden especially worrisome.