When Do Nudges Increase Welfare?

We use public finance sufficient statistic approaches to characterize the welfare effects of “nudges,” such as simplified information and warning labels, in markets with taxes and endogenous prices. While many studies focus on average effects, we show that welfare also depends on how the nudge affects the variance of choice distortions, and average effects become irrelevant with zero pass-through or optimal taxes. We implement the framework with experiments evaluating automotive fuel economy labels and sugary drink health labels. Labels decrease purchases of low-fuel economy cars and sugary drinks but may decrease welfare because they increase the variance of choice distortions. (JEL D18, D62, D83, D91, H21, L62, L66)