The retail access index considers both the quantity of retail jobs and the distance to those jobs relative to each Census block group. This variable uses a gravity model, a model that includes inverse distance weighting, that considers retail employment both in and adjacent to a given block group. This measure is superior to a retail jobs density measure, based on jobs only within a block group, because it provides a measure of opportunity to access retail employment by factoring in retail locations outside of the target block group. Access to retail employment is important in understanding the quantity of retail related jobs, as well as the proximity of retail destination development within a local area.
The retail access index utilizes a gravity model that leverages an inverse-square law to calculate the total number of retail jobs for every block group in the U.S. and divides by the square of the distance to each job. This variable allows for the evaluation of the quantity of jobs and the accessibility of job locations simultaneously.
Retail employment access index =
The MSA level value is the unweighted mean of the values of all block groups in the MSA.
This indicator was calculated by the U.S. Department of Housing & Urban Development (U.S. HUD), and U.S. Department of Transportation (U.S. DOT) using data from the sources listed below.
- U.S. HUD and U.S. DOT Location Affordability Index, 2013.
- Census Bureau, Longitudinal Employer-Household Dynamics (LEHD), 2014.
- Cevero, R. & Kockelman, K. (1997). Travel Demand & the 3 Ds: Density, Diversity & Design. Transportation Research Part D: Transport & Environment 2, 3, 199-219.