How does Infoshare provide information for geographic areas when data are not published for such areas?
Community Studies obtains from its data sources (government agencies, some commercial firms) data at the smallest geographic area at which it is publicly available, usually census tracts and zip codes. To provide data for other geographies, we have, over the past decade, developed a series of overlap factors which convert this small-scale data into these larger areas of special interest. Such overlap factors are based upon the distribution of residential housing, when this is available. In that case, the overlaps approximate as closely as possible the distribution of the population by residence. Where this residential data is not available, geographic overlap factors are derived using standard geographic mapping overlays. Overlap factors (for instance, the percentage of a zip code in a particular State Assembly District) are maintained to three significant figure accuracy (e.g., 12.3%). Therefore, data which may appear to have more than three significant figures should be treated caref
