PROBABILITIES AND HEALTH RISKS - A QUALITATIVE APPROACH

Health risks, defined in terms of the probability that an individual w ill suffer a particular type of adverse health event within a given ti me period, can be understood as referencing either natural entities or complex patterns of belief which incorporate the observer's values an d knowledge, the position adopted in the present paper. The subjectivi ty inherent in judgements about adversity and time Frames can be easil y recognised, but social scientists have tended to accept uncritically the objectivity of probability. Most commonly in health risk analysis , the term probability refers to rates established by induction, and s o requires the definition of a numerator and denominator. Depending up on their specification, many probabilities may be reasonably postulate d for the same event, and individuals may change their risks by decidi ng to seek or avoid information. These apparent absurdities can be und erstood if probability is conceptualised as the projection of expectat ion onto the external world. Probabilities based on induction from obs erved frequencies provide glimpses of the future at the price of accep tance of the simplifying heuristic that statistics derived from aggreg ate groups can be validly attributed to individuals within them. The p aper illustrates four implications of this conceptualisation of probab ility with qualitative data from a variety of sources, particularly a study of genetic counselling for pregnant women in a U.K. hospital. Fi rstly, the official selection of a specific probability heuristic refl ects organisational constraints and values as well as predictive optim isation. Secondly, professionals and service users must work to mainta in the facticity of an established heuristic in the face of alternativ es. Thirdly, individuals, both lay and professional, manage probabilis tic information in ways which support their strategic objectives. Four thly, predictively sub-optimum schema, for example the idea of AIDS as a gay plague, may be selected because they match prevailing Social va lue systems. (C) 1998 Elsevier Science Ltd. All rights reserved.