In the report by Freed and colleagues published last September,1 some key information was accidentally left out of the Method section.
The American Board of Internal Medicine (ABIM) maintains a combined list with the American Board of Pediatrics of all individuals who have successfully completed four years of medicine–pediatrics training. The report should have mentioned that as of May 12, 2003, when the study was carried out, there were 4,303 individuals who had completed training. Of these, 472 had completed at least three years of subspecialty training. In preparing the analysis that was reported, the authors used the data on all these 472 individuals. Of the remaining 3,831 individuals, the ABIM provided a random sample of 1,300. The sample was constructed using appropriate methodology and provided 80% power to detect a 10% difference both within the cartegories of each sample and between generalists and specialists. Responses were obtained from 805 of the generalist sample of 1,300, yielding a response rate of 62%, and from 274 of the 472 subspecialists sample, yielding a response rate of 58%.
1 Freed GL, Fant KE, Nahra TA, Wheeler John RC, and the Research Advisory Committee of the American Board of Pediatrics. Internal medicine–pediatrics physicians: their care of children versus care of adults. Acad Med. 2005;80:858–64.