Rules of Thumb in Household Savings Decisions: Estimation Using Threshold Regression

Abstract

The rules of thumb offered by financial advisors regarding how much to hold in liquid reserves vary widely and usually imply far greater sums than low-income households save. This paper seeks empirically-grounded insights into the minimum liquidity buffer needed by the average low-income household. First, we document diminishing benefits to liquid savings in terms of the likelihood of experiencing financial hardship. Then, we formalize this relationship with a theory of poverty traps. Finally, to observed data, we fit a regression kink model with an unknown threshold (kink) point that must be estimated. Our key finding is that the threshold point is $2,467 with a 95% confidence interval of $1,814–$3,011 (in 2019 dollars) or roughly 1 month of income for the average low-income household – which is far less than the savings amounts implied by common rules of thumb (typically 3–6 months of income). Theoretical evidence suggests that financial advice based on an empirically-estimated threshold point is welfare enhancing for households with naive perceptions of their probability of experiencing financial problems.