It’s worth taking the time to examine Sanders’s claim that the middle class is worse off now than in the past. He doesn’t cite a source for his statistic, but it seems to rely on looking at the median household income over time and adjusting for inflation using the Consumer Price Index (CPI).
This is a problematic methodology because it does not control for the well-known fact that the median household has itself grown smaller over time. Even if median income stayed the same over time, a decline in the number of people in the median household over time would lead to an increase in income per household member.
Additionally, Sanders’s statistic looks at income before taxes and transfers. Transfer payments and tax credits (like the Earned Income Tax Credit) make up a significant portion of income for many lower-income families. Not controlling for these factors understates their true economic well-being.
The figures cited by Sanders also fail to take into account the fact that a larger proportion of worker compensation comes in the form of non-cash benefits (such as health insurance) now than in the past.
Acording to research published by the National Tax Journal, “Broadening the income definition to post-tax, post-transfer, size-adjusted household cash income, middle class Americans are found to have made substantial gains,” amounting to a 37 percent increase in income over the 1979-2007 period.
Similarly, in 2014, the Congressional Budget Office found that adjusting for changing household size and looking at income after taxes and transfers, households in all income quintiles are much better off than they were a few decades ago.
The incomes of households in the three middle income quintiles grew 40 percent between 1979 and 2011. Somewhat surprisingly, given the histrionics about the state of America’s poor, income in households in the lowest quintile was 48 percent higher in 2011 than it was in 1979.
Research from the Federal Reserve Bank of Minneapolis comes to even more optimistic conclusions.
The Consumer Price Index is widely understood to overstate inflation — among other reasons, by failing to accurately account for improvements in quality and consumer substitutions for newer or cheaper goods — which is why the Federal Open Market Committee uses an alternative measurement for inflation, the Personal Consumption Expenditures (PCE) price index, which includes more comprehensive coverage of goods and services than the CPI.
If the CPI does, in fact, overstate the extent to which prices rise over time, then it also consequently understates the growth in real, inflation-adjusted incomes over time.
Indexing median household income (post taxes and transfers) to inflation using the PCE, rather than the CPI, and adjusting for the long-run decline in household size shows that median incomes have “increased by roughly 44 percent to 62 percent from 1976 to 2006.”
Moreover, the focus on statistical categories ignores what is happening at the level of individuals and households, which may move up or down the income ladder, through different income quintiles. And studies have consistently shown that this income mobility has not changed in decades.
While the rate of growth for some income categories in recent years has been sluggish, the claim that middle incomes are declining precipitously is false. Based on these findings, it seems appropriate to conclude that Sanders’ claim that there exists a “long-term deterioration of the middle class” is patently untrue.