Information frictions are often invoked to explain low levels of international trade beyond those that measured trade frictions (tariffs, transportation costs, etc.) can explain. But to explain why international trade is lower then domestic trade, home firms have to know something that...

We survey work using Bayesian learning in macroeconomics, highlighting common themes and new directions. First, we present many of the common types of learning problems agents face---signal extraction problems---and trace out their effects on macro aggregates, in different strategic settings....