Presents can come in black boxes, too.

]Th e value of nonrandomized studies of disease etiology conducted among individuals within a given population-"risk factor" epidemiology-no doubt has been ques tioned for as long as there have been such studies. However, since 1988, when Alvan Feinstein' claimed that epidemiologic methods currently in use "need substantial im provement to produce trustworthy scientific evidence," questioning of this sort seems to have intensified.24 In his article5 elsewhere in this issue, Sander Greenland has described 2 bases for the concern with "risk factor" epidemiology: 1) in many studies, there are no strong prior hypotheses for associations that are observed (ie, a "black box" is present), and a considerable number of these associations will in fact not be genuine; and 2) the enumeration of exposure-disease associations can generate concern among many mem bers of the public, and ultimately as much or more harm than good could ensue. However, Greenland points out-as was done in the very first issue of Epidemiology, by persons responding to Feinstein's critique67 -that even in the absence of a compelling hypothesis, carefully made observations in epidemiologic studies can play a role in the development of theories of etiologic pathways leading to the occurrence of diseases, and so such observations should be welcomed, not shunned. Indeed, the years since the publication of Feinstein's commentary have seen instances in which "black box" epidemiologic studies have identified associations that have led to the development of widely accepted causal hypotheses (eg, the etiologic role of the prone sleeping position in sudden infant death syndrome8) and resulting beneficial interventions (eg, parental education regarding infant sleeping position9). All of us, whether we are proponents or opponents of "risk factor" epidemiology, share a concern for the excessive (from a scientific point of view) attention paid by the news media to the results of the most recently published or presented epidemiologic research. There seems to be too little attention to the quality of the work or to the aggregate results of all studies of the question at hand. Yet, it would be sad if such public attention to communication among epidemiologists in journals or at meetings discouraged dissemination of (in Greenland's words) "the facts that require explanation by theories." Cognizant that "eavesdropping" by nonprofessionals does indeed take place, it behooves epidemiologists to follow Greenland's admonition to indeed emphasize the facts and the nature of the study that led to their generation. To the extent that, as a consequence of their work, epidemiologists would like to draw broader etiologic conclusions or suggest policy implications, I would add that these statements should be based on all relevant research, not just on the findings presented by the investigators in a particular report. Greenland did not address the attack on "risk factor" epidemiology that has been directed, not toward its methods, but rather to the subject of its inquiries. Pearce,10 in advocating that greater attention be paid to potential etiologic factors affecting whole