What is the statistical model behind the small area estimation process?
The statistical model used to produce the indirect county estimates of the percentages of adults lacking Basic Prose Literacy Skills (BPLS) was developed using the 2003 NAAL data; the same modeling approach was then applied to the 1992 NALS data. A Hierarchical Bayes (HB) model was adopted using a Markov Chain Monte Carlo (MCMC) method, and was implemented using the WinBUGS software (Lunn et al. 2000). The key component of the approach was to develop a logit model (linear logistic regression model) to predict the direct county percentages of adults lacking BPLS for counties with sample respondents from a set of auxiliary variables that were available and measured consistently for all counties. Non-informative prior distributions were used for the model parameters. The posterior distributions for the model parameters were used to produce the indirect estimates for all U.S. counties based on their values for the predictor variables and incorporating information about the direct estiamtes
