The survey collects information on the general and health characteristics, insurance coverage, and health care use of all people in sampled households. The researchers used the survey data to identify adults older than 18 years of age who used at least 1 outpatient drug that was available in both generic and brand-name forms (outpatient drugs are drugs used outside of the hospital). The survey also includes information about the amount spent on each brand-name drug by both individuals and their insurance programs. Next, they calculated the potential savings of replacing brand-name drugs with generic drugs, after calculating the average cost of each generic drug and the corresponding brand-name drug for over 7000 drugs used by adults in this sample. Last, they estimated the potential per-person and total savings of generic substitution.