Most study populations have not had available data on socioeconomic factors at birth and in adulthood. Studies with SES data have found that the inverse trend is not substantially altered by adjustments for these factors. The Harvard Nurses Study had occupation data on parents when the nurses were 16 years of age. The Rancho Bernardo study, discussed earlier, is a homogeneous SES population as is the Male Health Professionals Study. In a study of men in South Wales investigators had information on father's social class, men's own social class, marital status as well as other established risk factors for coronary heart disease (Frankel S, et al. Lancet 1996;348:1478-80).