from The Inequality Hype by Neil Gilbert in The American Interest:
However as Richard Burkhauser pointed out in his presidential address to the Association for Public Policy Analysis and Management, the market income of a tax unit is a poor indicator of how much money families actually have to live on.7A more inclusive measure of the income that remains in households after subtracting what they must pay in taxes and adding the money they receive through government transfers transmits a different image of the American experience. Applying these criteria, instead of a decline we see a 32 percent increase in the mean income of the poorest fifth between 1979 and 2007. (Table 1) Overall, this broader measure still reveals a rise in inequality during that period as the mean income of those in the top bracket climbs by 54 percent.8 But it, too, is incomplete.
Along with taxes and transfers, the most authoritative and extensive measure of income also incorporates capital gains. Along with Burkhauser and his colleagues, the nonpartisan Congressional Budget Office (CBO) agrees that a comprehensive definition involves the sum of market income adjusted for taxes, household size, cash and in-kind transfers, and capital gains.9 However, the consensus unravels over the issue of exactly how to value capital gains. The basic choice is whether to focus on the total taxable gains realized in the year capital assets are sold or the annual change in value of capital assets whether or not they are sold. This is not just a matter of bookkeeping. The choice to include either realized or accrued capital gains in the calculation of annual income has a considerable impact on the rates of inequality.
The CBO favors the use of realized capital gains that are reported on tax returns. After factoring in the impact of taxes, capital gains, and government transfers the CBO data reveal a sharp decline in inequality compared to when it is measured solely by market income. According to these figures, between 1979 and 2010 the household income in the bottom quintile increased by 49 percent, the income in the middle three quintiles increased on average by 40 percent, and those in the highest bracket increased by 71 percent.10 While incomes increased across the board, the largest gains registered on the two ends of the income distribution. These findings temper progressive arguments that focus on the increasing inequality of market incomes to demonstrate the need for greater social welfare spending.
This is a very short excerpt from a lengthy article that focuses on just one consideration, capital gains measurement, and its impact on the measurement of inequality. The more salient point is that inequality is far more difficult to measure than most realize and the main stream reporting does not even try to comprehend the difficulty and thus the shallowness of their reporting on this issue