First-differenced estimation is ideal for obtaining causal effects of explanatory variables that are constant over time.

With railroads, considerable regulatory energy was spent trying to solve the so-called ______________________.

Fill in the blank(s) with the appropriate word(s).

In equilibrium, rent seeking eliminates the

A) deadweight loss. B) economic profit. C) consumer surplus. D) demand for the product. E) opportunity to price discriminate.