First, the income definitions are different: Household income is based on a survey that asks people about only their income, not their employer-provided benefits and retirement contributions. In a previous post, we showed that these benefits have increased relatively more than wages. Real GDP includes all income in the economy. Second, if the distribution of income becomes more unequal, then the median decreases while the mean stays put. How much each of these contribute to the remaining gap can only be determined with a look at the microdata.