[gusgus01]

Yes, and the rest of the article discussed how they actually have revisited some of their numbers and links to their reports where you can read about their methodology and decide if it's comprehensive enough.

To quote the article: "Debates over measuring effective tax rates have been lively because measuring taxes and incomes is complex and involves judgement calls (and the political stakes are high.) We applied a simple and replicable method to a single, publicly available source of data to estimate the effective tax rates of high-income taxpayers that avoids making assumptions about grey areas like unrealized capital gains and corporate tax burdens."