Growth, inequality, and mobility
Separate average growth, distribution, and mobility.
An increase in average income does not imply equal gains. Original example: incomes of 10 and 30 average 20. Later, incomes of 10 and 50 average 30. The average rises 50%, but the first person gains nothing.
Inequality describes differences; mobility concerns changes in people’s position or income over time. Intergenerational opportunity is a further question requiring appropriate data.
Check income versus wealth, individuals versus households, before versus after tax, and adjustment for prices. A single statistic summarises information while losing detail. Explain your measure rather than choosing whichever favours a prior position.
Make your understanding visible
Ask three statistical questions about “this place became richer.”
Compare with a reference response
Total, per-capita, or median? Adjusted for price changes? Similar gains across income groups? Apply these questions whether you favour or doubt the claim.