then the consumer becomes aware and decides to re-optimize her plan election. Here ~vi;t is a
function of consumer demographics related to health status and sensitivity to changes in plan
characteristics: age groups, income quartiles, gender and race. Heterogeneity in search costs is an
important part of the model and the data, as can be seen for example in Table 220. We also include
year xed eects in ~vi;t to account for dierences in the environment across our three dierent
enrollment periods. We expect that the amount and nature of advertising and of pharmacy and
government outreach aected consumer attentiveness, and we expect these factors varied over time.
The second stage of the model examines how consumers who have decided to re-optimize choose
whether to switch and to which plans. We assume that if equation (4) holds then consumer i makes