Column · cost of living distribution
Housing, transport, food and childcare vary by an order of magnitude within a single city. A single average describes nobody; it describes the arithmetic of everyone.
The cost of the specific bundle they would buy: the neighbourhood, the commute, the school, the diet. Those four choices account for most of the variance, and none of them is captured by a city-level average.
As a comparison between places, not as a budget for a person. "X is 20% more expensive than Y" is defensible. "You need $Z to live in X" is not.
People move based on averages and discover their actual bundle costs 40% more. The error is not in the data; it is in the question the data was asked to answer.
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