where expected OOP spending excluding premium (TrO^OPi;j;t) is calculated using the method
described in Section 4, Premiumj;t and Dedj;t are annual premiums and deductibles and Gapj;t
is an indicator for any coverage in the gap. Xj;t are non-price plan characteristics including an
indicator for enhanced plans and brand xed eects (dened at the carrier rather than the plan
level) and i;j;t is an IID extreme value type 1 error term (assumed to be independent of vi;e;t). In
the reported specications we use chronic TrOOP as our measure of OOP costs, since acute TrOOP
may be measured with error while this is unlikely to be the case with chronic TrOOP.21 Note that
a consumer who could calculate expected costs perfectly would value a given change in TrOOP and
premium equally, as they are both measured in dollars. We allow consumers prompted to search
by shocks to premiums to place additional weight on premiums. Consumers experiencing shocks
to coverage, or acute shocks, can place additional weight on the plan oering gap coverage.