Heredity, stress and blood pressure, a family set method--I : Study aims and sample flow

Abstract

This first article, in a series of five, describes the method of sampling family sets. Family sets are composed of three persons having a genetic relation: an index, his/her sibling and first cousin, and two persons having an environmental nexus, a spouse of index and an unrelated person matched to the index. The target populations were four census areas in Detroit, a black high stress area, a black low stress area, a white high stress, and a white low stress area. These areas were selected by a factor analysis of census rates which indicated extremes of Stressor conditions. Within each area a complete census was taken, potential sample members were selected and verified by another interviewer, then assigned as an index; sibs and first cousins, selected as closest in age to index, were verified independently, then an unrelated person was chosen, and all five persons were independently interviewed and blood pressures taken. This article details the full sampling process in each of the four census areas, and tests the final sample of 461 family sets in several ways which confirmed expectations.