When full insurance may not be optimal: The case of restricted substitution
即使保费大幅补贴，仍有很多人不买健康保险。本文提出一种新解释：当人们无法自由权衡健康与财富时，即使保费精算公平，也可能不买完全保险，这在低收入人群中尤为常见，影响全民健康覆盖目标的实现。
Even when heavily subsidized, a substantial portion of people choose to forgo purchasing health insurance coverage. In this note, I introduce an explanation for this phenomenon which does not assume choice errors, incorrect beliefs, differently priced uncompensated care, or information asymmetries. When individuals are incapable of freely trading off health and wealth and the initial allocation of goods is suboptimal from their perspective, the standard result of demand for actuarially fair insurance in a single good world does not generalize to the health insurance context. Thus, people might not purchase full health insurance coverage even if it is priced at actuarially fair levels. I argue that this situation is particularly likely to occur in the low-income population, and hence it is relevant for the achievement of universal health coverage.