Compare the right things
Try a clearly labeled teaching example and learn how to compare compatible places and periods.
Match the labels before the numbers.
Compare the same measure, population, units, geography definition, and compatible periods. A family median, a household median, and a housing-unit median are different measures.
A place comparison describes differences. It does not establish what caused them. A change over time also needs consistent methods and a check for uncertainty.
Try one fair comparison.
These numbers do not describe a real place or family. Change them to see the arithmetic, then ask whether the labels and sources would match in a real study.
A numerical difference does not explain the cause or establish statistical significance. If the first value is zero, a relative percentage change is not defined.
Available evidence
The Bexar County snapshot is available. A full place-to-place or historical comparison dataset is not released yet.
Inspect the local example ↗