A social network approach to corroborating the number of AIDS/HIV + victims in the US

Accurate estimates of the sizes of certain subpopulations are needed to inform important public policy decisions in the US. Laumann et al. (1989, 1993) have attempted to assess the accuracy of the reported data on the incidence of AIDS in the US, collected by the Centers for Disease Control and published in the AIDS Weekly Surveillance Reports (AWSR) and HIV/AIDS Surveillance Reports (HASR), by comparing these data with response data from the 1988, 1989, 1990 and 1991 General Social Surveys (GSSs). To establish reference comparison subpopulations, they did a similar assessment of the reported numbers of homicides during previous 12-month periods, published in the Unified Crime Report (UCR) and the Vital Statistics of the United States (VSUS), comparing these data with other response data from these same GSSs. The GSS data were compared with the AWSR, HASR, UCR and VSUS figures by sex, race, ethnicity, age, and region of the US. Their results for homicide victims are reasonably similar to the UCR and VSUS figures for these categories, while their results for AIDS victims are reasonably similar to the AWSR and HASR figures only for sex and age. There is then the question of whether reported total figures for the incidence of homicides and AIDS (as well as suicides during a previous 12-month period) are reasonably accurate. There is concern that there is significant undercounting of the total incidence of AIDS. Here we investigate this issue using a simple mathematical model of social networks, some elementary social theory, recent estimates of average personal network size in the US by the authors, and response data from the 1988, 1989, 1990, 1991 and 1993 GSSs. Assuming the average personal network sizes of homicide victims, suicide victims and AIDS victims are about the same as those for the general US adult population, we test as null hypotheses the propositions that the incidence of homicides reported in the UCR, of suicides reported in the VSUS, and of AIDS reported in the AWSR and HASR are accurate. Our analysis does not detect a significant inaccuracy in the reported figures for homicides. For suicides and AIDS, however, we encounter discrepancies of varying degrees, suggesting that either the reported figures are overcounts, AIDS and suicide victims have significantly smaller average personal network sizes than the general US adult population (smaller for AIDS victims than for suicides), or else the GSS respondents significantly underreported their personal knowledge of suicide and AIDS victims, either because they did not know that some of the people they know committed suicide or have AIDS, or because they falsely state their lack of knowledge of such victims, perhaps because of the stigma attached to such associations. These issues are illuminated by the results from an earlier survey of personal network size in Gainesville, Florida, and a previous national survey among surgeons, which suggest that lack of knowledge of personal network members who have AIDS seems to play a major role in explaining the discrepancies with the reported figures for AIDS.