Aggregation Reversals and the Social Formation of Beliefs

In the past two elections, richer people were more likely to vote Republican while richer states were more likely to vote Democratic. This switch is an aggregation reversal, where an individual relationship, like income and Republicanism, is reversed at some level of aggregation. Aggregation reversals can occur when an independent variable impacts an outcome both directly and indirectly through a correlation with beliefs. For example, income increases the desire for low taxes but decreases belief in Republican social causes. If beliefs are learned socially, then aggregation can magnify the connection between the independent variable and beliefs, which can cause an aggregation reversal. We estimate the model’s parameters for three examples of aggregation reversals, and show with these parameters that the model predicts the observed reversals. * Glaeser thanks the Taubman Center for State and Local Government for financial support; Sacerdote thanks the National Science Foundation. Gary King and Jose Scheinkman provided helpful comments. Giacomo Ponzetto did heroic service discussing and improving the paper.