One of the big problems with our official median income statistics is that the government only estimates the median income of households and we care about the welfare of people, not households. Household size has dropped which has tended to make median household income undercount the welfare of individuals because fewer people are dividing up household income. The graph below shows how the approximate average number of people per household has been declining:
If we divide median household income by the average number of people per household, we can get the approximate median income per person in the US.
This isn’t the best way to calculate this because it will have some aggregation errors due to using the average household size rather than dividing up each household’s income, but it is better than using the raw median household income data. The other things this doesn’t include are government taxes and transfers, the value of private benefits like employer-provided health insurance, and the imputed rent from owner-occupied housing.
Adjusting for household size doesn’t actually change much in the data since 1990 because the average household size has been very stable, but it would have been useful in the 1950s and 60s. In the available FRED data, there is less than a 2% difference between the two.
In any case, as with median household income it is a better indicator of economic welfare than real mean GDP: