Demand heterogeneity in insurance markets: Implications for equity and efficiency

Abstract

In many markets insurers are barred from price discrimination on consumer characteristics like age, gender, and medical history. By themselves, such restrictions are known to exacerbate adverse selection problems. But the conventional wisdom—widely reflected in policy—is that with regulatory tools like premium subsidies, it is possible to address selection and induce efficient plan choices without price-discriminating. In this paper, I show why this conventional wisdom is wrong: As long as different sets of consumers (men and women, rich and poor, young and old) differ in their willingness-to-pay for insurance conditional on the losses they generate, then price discrimination across such groups is welfare-improving. The conventional wisdom is wrong because it implicitly assumes a one-to-one mapping from insurable risk to insurance valuation. I show that demand heterogeneity that breaks this one-to-one relationship is empirically relevant in a consumer health plan setting. Younger and older consumers and men and women reveal strikingly different demand for health insurance, conditional on their objective medical spending risk. This implies that these groups must face different prices in order to sort themselves efficiently across insurance contracts. The theoretical and empirical analysis highlights a previously unexplored, but fundamental, tradeoff between equity and efficiency that is unique to selection markets.