One goal of our small area work is to provide measures of the uncertainty surrounding the estimates. The model-based estimates shown in the tables are accompanied by their 90-percent confidence intervals constructed from estimated standard errors.
We assume that the variance at the national level and the variance of the CPS ASEC universe estimates are negligible. The posterior standard deviations of the aggregated state-level estimates need only be adjusted for correlations between the counties, which is handled by the estimation procedure, and multiplied by the raking factors. Confidence interval half-widths for estimated numbers are rounded up to preserve coverage probabilities. Note also that the widths of the confidence intervals are the same for the number of insured and uninsured. This follows from the fact that the two must add up to the national CPS ASEC estimate which has negligible variance.