martha farnsworth riche is the former director of the u.s.bureau, who was instrumental in designing the 2000 census. dr. riche: demography is really the science of studying people or studying populations. in the strictest sense, it refers to studying the growth or the decline of populations in terms of, obviously, people being born, people dying, and then people moving in or moving away. ople are the focus of policies. they're the focus of programs. they're the focus of advertising, entertainment, what have you. but they're the common denominator. we don't have an ideology. we count and we place and we describe. narrator: in the united states, the population is measured by the u.s. census. every 10 years, the census counts the number of people living in every household across the nation. do this. narrator: the census bureau also conducts additional surveys on such topics as economics, housing, and health. demographers use data compiled through the census and additional surveys to study population dynamics. a question that people have about th