where average APR refers to the average interest rate paid by all revolvers. This is a modification of the Cude(1987) measure that uses the “best” and worst” choices.
Our rationale for using the current APR as the worst choice is that consumers may not be starting the search without a credit card -- they would necessarily consider their current card as a baseline. We used the average APR as our best choice to control for the effects of teaser or introductory rates; otherwise, our estimates could be biased too far upward. Following Stigler’s
(1961) formation search approach, if a consumer does not conduct any search when choosing a credit card, the expected value of the APR is the average APR in the market. The difference between the consumer’s current APR and the average APR is a function of the consumer’s information search. Thus, by multiplying any difference in APRs by the outstanding balance, we
can estimate the dollar savings attributable to search.