To the Editor: The article by Schaffer et al. (Feb. 11 issue)1 raises some salient questions about the importance of and the difficulties inherent in validating physicians' credentials. The authors were able to get information for this study from data often kept confidential. We have concerns about the success with which less persistent or less well informed persons can find out about prospective employees or personal physicians. In our study,2 we were unable to get any independently verified information about doctors' clinical training, beyond board certification, from the usual published sources. How, we wonder, does the average consumer fare? In. © 1988, Massachusetts Medical Society. All rights reserved.