This is an invited chapter for the forthcoming Volume 4 of the Handbook of Industrial Organization. We present empirical models of demand and supply in differentiated products industries with an emphasis on the key ideas arising from the recent applied literature. We start with a discussion of...

This paper specifies an estimable dynamic model of sequential discrete choices in a controlled jump-process framework. We study sufficient conditions under which the agent's optimal policy is stationary. We show that the observable event histories at the micro-level are sample paths of a...