THEORY AND METHODS OF EPIDEMIOLOGIC STUDY OF HOME ACCIDENTS

Problems in the design of epidemiologic studies may be categorized conveniently into those related to ascertainment and those concerned with sampling. Sampling problems confronted in home accident studies are not different, in any essential way, from those encountered in any other epidemiologic studies. With reference to sampling, the epidemiologic critics are far in advance of epidemiologic practitioners, so that the latter have yet to propose a study which the former cannot demolish by attacking the sampling procedures. The critics apparently have already discovered a whole host of biases which will only be demonstrated by studies yet to be devised. For these reasons, sampling problems will be treated only briefly in this report, where they are inextricably involved with the business of ascertainment. Problems of ascertainment in home accident studies do present some special, though perhaps not unique, features. Ascertainment is the process of acquiring desired information. The term carries the connotation that this is an active quest, involving a search for the data. Each item of information sought must be specified, defined, the need for it justified, and the method by which it is to be collected established. Generally, more attention is paid to the disease diagnosis than to other characteristics of the host. On logical grounds, one may hold that a correlation of the occurrence of disease with some other factor, such as age, may be rendered invalid as certainly by errors in recording age as by errors in recording the disease, but this has little emotional appeal and in practice we continue to expend the most concern on those things that interest us most. Therefore, this paper will be devoted largely to problems of ascertainment of cases. Many of the ideas referable to this characteristic of the host can be generalized to the ascertainment of other host and environmental characteristics. To study home accidents requires that home accidents be defined and immediately home accident studies are in trouble. To my knowledge there is no satisfactory definition of an accident, and no satisfactory means of separating completely home accidents from other forms of accidents. While a number of recent publications on home accidents have failed to present a definition, Suchman and Scherzer,’ in an excellent review, discussed a variety of definitions which have received some acceptance. Most of them incorporate a statement of recognizable injury or loss. Some refer to “chance” events, which connotes that accidents are distributed randomly, and this is clearly not true. The United States Public Health Service publication “Uniform Definitions of Home Accidents,’” refers to an accident as a sequence, chain of events, or series of interactions between the