Methods

The original ECA study included two waves of interviews in the early 1980s at five sites across the United States. At the Baltimore site, a sample of 4,238 household residents was created with probability estimates to represent the target population of the 175,211 residents of East Baltimore. In the first wave, a total of 3,481 participants (82% of 4,238 designated) were interviewed with the Diagnostic Interview Schedule (DIS)(4). In a blind, independent follow-up called the Clinical Reappraisal study, psychiatrists examined a subsample of 810 participants from the total 3,481 (23%), which was stratified to include participants with specific DIS diagnoses of a mental disorder, as well as a random sample of the population (5).