Income Mobility is Much More Important Than Rising Income Inequality or Stagnating Household Income, and We Have a Lot of It (Mobility)
We hear a lot these days about "increasing income inequality" and "stagnating household income," but those discussions rarely include what is probably the most important factor when it comes to income over time: income mobility. In fact, even if: a) income inequality was increasing over time, and b) median household income was stagnant over time, those outcomes wouldn't necessarily be a problem if there was significant income mobility. Reason? If there is substantial movement of households over time from lower-income to higher-income quintiles, households may only be earning the median household income for a short period of time on their way up to a higher quintile.
In other words, it's more likely that most households are "typical" or at the "median" level" only temporarily on their way to a higher income group. The fact that median household income might be stagnant over time seems far less important than what happens as households exceed median income and move up to a higher-income category. In the case of significant income mobility over time, wouldn't households actually benefit from increasing income inequality over time if that allowed them to earn higher incomes relative to the median or low-income quintiles once they arrived at one of the top two quintiles?
Most of those complaining about income inequality and stagnating income seem to statically assume that households or individuals stay in the same income group (by quintile, or the "top 1%," "top 10%," bottom 50%, median income, etc.) forever, with no movement over time. If we assume that you're stuck in the bottom income quintile for life, or even earn the median household income for life (both highly unrealistic), then the concerns about rising income inequality or stagnating median household income have greater strength. But with dynamic movement over time in the income of households and individuals, the "problems" of income inequality and stagnating income seem much less important, and might even be "non-problems."
Thomas Sowell offers this key insight (emphasis added):
For example, recent research from the Federal Reserve Bank of Minneapolis is summarized in the table above, based on income data from the Panel Study of Income Dynamics that followed the same households from 2001 to 2007. The empirical results answer the question: For households that started in a given earnings quintile (20 percent group) in 2001, what percentage of those households moved to a different income quintile over the next six years? Short answer: a lot.
Read more here at The Enterprise Blog.