The 1980s opened a discussion of the varying nature of health in different segments of the United States. Falling under the rubric of "health disparities," a great deal of research has been published demonstrating the substantial differences in health status within a population. The causes of health disparities are varied and not always clear but most researchers agree that disparities are a reflection of social and economic inequities and political injustice. One of the obstacles to addressing disparities is the lack of meaningful health data especially for vulnerable populations, which is...