Mixed Race Studies

The Population Variance of the Proportion of Genetic Admixture in Human Intergroup Hybrids

Proceedings of the National Academy of Sciences
December 1971
Volume 68, Number 12
pages 3168–3169
PMCID: PMC389614

T. Edward Reed, Professor of Zoology and Anthropology; Associate Professor of Paediatrics
University of Toronto, Toronto, Canada

For each individual in a human hybrid population there is a proportion μi, whose value is usually unknown, that expresses the fraction of his genes deriving from a specified parental population. The distribution of these individual proportions about the mean proportion μ is not known for any large hybrid population in man. It is of interest to know whether the population variance of individual proportions (μi) can be estimated from the variation between different, independent estimates of the mean proportion (μ).This possibility was tested with data on Negroes of the Oakland, California area, by the use of some of the principles of analysis of variance. Even with a large sample and the useful Duffy blood-group system to indicate admixture, almost no information about the population variance of individual proportions is provided by between-sample variation in estimates of μ. It is concluded that group data on admixture proportions usually do not give useful information about the population variance. It is further concluded that a recent estimate of this variance by Shockley is in error.

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The multiple-race population of the United States: Issues and estimates

Proceedings of the National Academy of Sciences (PNAS)
2000-05-23
vol. 97 no. 11
pages 6230-6235

Joshua R. Goldstein

Ann J. Morning, Assistant Professor of Sociology
New York University

This paper presents national estimates of the population likely to identify with more than one race in the 2000 census as a result of a new federal policy allowing multiple racial identification. A large number of race-based public policies—including affirmative action and the redistricting provisions of the Voting Rights Act—may be affected by the shift of some 8–18 million people out of traditional single-race statistical groups. The declines in single-race populations resulting from the new classification procedure are likely to be greater in magnitude than the net undercount in the U.S. census at the center of the controversy over using census sampling. Based on ancestry data in the 1990 census and experimental survey results from the 1995 Current Population Survey, we estimate that 3.1–6.6% of the U.S. population is likely to mark multiple races. Our results are substantially higher than those suggested by previous research and have implications for the coding, reporting, and use of multiple response racial data by government and researchers. The change in racial classification may pose new conundrums for the implementation of race-based public policies, which have faced increasing criticism in recent years.

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