Source: Wojciech Kopczuk, National Bureau of Economic Research (NBER), NBER Working Paper No. w20734, December 2014
From the abstract:
I discuss available evidence about the evolution of top wealth shares in the United States over the last one hundred years. The three main approaches – Survey of Consumer Finances, estate tax multiplier techniques and capitalization method – generate generally consistent findings until mid-1980s but diverge since then, with capitalization method showing a dramatic increase in wealth concentration and the other two methods showing at best a small increase. I discuss strengths and weaknesses of different approaches. The increase in capitalization estimates since 2000 is driven by a dramatic and surprising increase in fixed income assets. There is evidence that estate tax estimates may not be sufficiently accounting for mortality improvements over time. The non-response and coverage issues in the SCF are a concern. I conclude that changing nature of top incomes and the increased importance of self-made wealth may explain difficulties in implementing each of the methods and account for why the results diverge.