Constructing a Time-Invariant Measure of the Socio-Economic Status of U.S. Census Tracts
Jeremy Miles, RAND Corporation
Margaret M. Weden, RAND Corporation
Diana Lavery, RAND Corporation
Jose Escarce, University of California, Los Angeles and RAND Corporation
Regina Shih, RAND Corporation
Contextual research on time and place requires stable measurement of neighborhood conditions for unbiased inferences. We develop such a time-invariant measure of neighborhood socioeconomic status (NSES) using exploratory and confirmatory factor analyses fit to census tract data from the 1990 and 2000 U.S. Censuses and the 2008-2012 American Community Survey. A single factor model fit the data well at all three times, and factor loadings –but not indicator intercepts– could be constrained to equality over time without decrement to fit. After addressing remaining longitudinal measurement bias, we found that NSES increased from 1990 to 2000, and then – consistent with the timing of the “Great Recession” -- declined in 2008-2012 to a level approaching that of 1990. Our approach for evaluating and adjusting for time-invariance is not only instructive for studies of NSES but also more generally for longitudinal studies in which the variable of interest is a latent construct.