Economists have studied economic events by looking at demographic variables for a long time. But all too frequently analysts and other data users do not realize the deficiencies in what look like excellent quantitative measuresthe black population, single mothers who are Hispanics, families of Vietnam veterans, so forth. In fact, changing social attitudes have changed language, including that used to collect data on people’s racial and ethnic identities. It is quite impossible, for example, to compare the number of black people today with that existing before 1970 because the term “black” was not used. Many earlier tabulations show white and non-white, with Negro as a subset of non-white. In common speech, the term “colored people” was preferred, “Negro” being a more formal term.1