Some on the left of the political spectrum argue that we have witnessed a stagnation of median household income in the U.S. This seems to be their evidence that lower tax rates and increasing reliance on markets to allocate goods are failed policies. A key problem with this story is that as Americans (and others around the world) get richer, the propensity to live in households with less people is increasing. So, if we are attempting to use median household income as a metric of well-being, we are losing site of the fact that the reason that Americans move into homes with fewer people is because that prefer it! So, housheold incomes are less because there are fewer earnes in each house. Politicians that focus on this metric as proof that the policies haven't worked either don't understand this point or are liars.