Why do population counts for the same geographic area sometimes seem to differ?
Counties are defined two ways. One uses Census boundaries (“actual”) versus a ZIP-defined county boundary. ZIP code areas often cross county boundaries. This means a ZIP code definition of a county can differ from the actual boundary, and the population counts differ because they are defined by different geographic boundaries. This is most frequently seen in hospitalization data. In this assessment topic, the population figures are given for ZIP code boundaries–and may be aggregated to the group of ZIP codes that most closely define a county’s boundary–because hospitalization numerator data (i.e., counts of hospitalizations) are only available by ZIP code.
Related Questions
- Why are signals and counts different if I switch between searching by county and by hospital for my geographic area in the emergency department data?
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- Why do population counts for the same geographic area sometimes seem to differ?
