Context.-This study examined the impact of retracted articles on biomedical communication. Objective.-To examine publications identified in the biomedical literature as having been retracted, to ascertain why and by whom the publications were retracted and to what extent citations of later-retracted articles continue to be incorporated in subsequent work. Design.-A search of MEDLINE from 1966 through August 1997 for articles that had been retracted. Main Outcome Measures.-Characteristics of retractions and citations to articles after retraction. Results.-A total of 235 articles had been retracted. Error was acknowledged in relation to 91 articles; results could not be replicated in 38; misconduct was evident in 86; and no clear reason was given in 20. Of the 235 articles, 190 were retracted by some or all of the authors; 45 were retracted by a person or organization other than the author(s). The 235 retracted articles were cited 2034 times after the retraction notice. Examination of 299 of those citations reveals that in only 19 instances was the retraction noted; the remaining 280 citations treated the retracted article either explicitly (n = 17) or implicitly (n = 263) as though it were valid research. Conclusion.-Retracted articles continue to be cited as valid work in the biomedical literature after publication of the retraction; these citations signal potential problems for biomedical science.

Careful study of medical informatics research and library-resource projects is necessary to increase the productivity of the research and development enterprise. Medical informatics research projects can present unique problems with respect to evaluation. It is not always possible to adapt directly the evaluation methods that are commonly employed in the natural and social sciences. Problems in evaluating medical informatics projects may be overcome by formulating system development work in terms of a testable hypothesis; subdividing complex projects into modules, each of which can be developed, tested and evaluated rigorously; and utilizing qualitative studies in situations where more definitive quantitative studies are impractical.