As part of the series of the "Finance Research Seminar", VGSF welcomes Michaela Pagel from the Graduate Business School of Columbia University to present her research paper.
Does Saving Cause Borrowing?
We study whether or not nudging individuals to save more has the unintended consequence of additional borrowing in high-interest unsecured consumer credit. We analyze the effects of a large-scale experiment in which 3.1 million bank customers were nudged to save more via (bi-)weekly SMS and ATM messages. Using Machine Learning methods for causal inference, we build a score to sort individuals according to their predicted treatment effect. We then focus on the individuals in the top quartile of the distribution of predicted treatment effects who have a credit card and were paying interest at baseline. Relative to their control, this group increased their savings by 5.7% on average or 61.84 USD per month. At the same time, we can rule out increases in credit card interest larger than 1.25 USD with 95% statistical confidence. We thus estimate that for every additional dollar of savings, individuals incur less than 2 cents in additional borrowing cost. This is a direct test test of the predictions of rational co-holding models, and is an important result to evaluate policy proposals to increase savings via nudges or more forceful measures.