Why is Productivity Correlated with Competition?

The correlation between productivity and competition is an oft–observed but ill–understood result. Some suggest that there is a treatment effect of competition on measured productivity, e.g. through a reduction of managerial slack. Others argue that greater competition makes unproductive establishments exit by reallocating demand to their productive rivals, raising observed average productivity via selection. I study the ready-mix concrete industry and offer three perspectives on this ambivalence. First, using a standard decomposition approach, I find no evidence of greater reallocation of demand to productive plants in more competitive markets. Second, I model the establishment exit decision and construct a semi-parametric selection correction to quantify the empirical significance of treatment and selection. Finally, I use a grouped IV quantile regression to test the distributional predictions of the selection hypothesis. I find no evidence for greater selection or reallocation in more competitive markets; instead, all three results suggest that measured productivity responds directly to competition. Potential channels include specialization and managerial inputs.