Mobility is typically defined in terms of moving between income quintiles in the population -- relative, not absolute. If the income range of the quintiles is very compressed (i.e. everyone's income is close to the median) then a small change in absolute income can lead to a large change in income percentile. Compared to places with higher income variance, this tends to overweight the "mobility" of places with low income variance. At the very least it produces a misleading result relative to what most people would define as meaningful mobility.

The same problem applies to comparing mobility between countries. If you have someone with the same (PPP) wage in the lower quintiles in Denmark and the USA, a $20k increase in absolute income in Denmark will cause a big jump in the quintile (and therefore "mobile") and a $40k increase in absolute income in the USA won't even though it is twice the real gain! Simply due to the fact that Denmark has low income variance and USA has high income variance. Income mobility measures that don't adjust for variance tend to produce misleading results when there are significant differences in income variance in the sample population.

If Utah has a relatively low income variance (not a lot of poor, not a lot of rich) then it will lead to percentile based mobility measures that are less meaningful than States with higher income variance.

The thing is, Utah has never had a truly poor population. They aren't raising people out of poverty, but it's growing fast and most of the people who move there are relatively rich compared to the general population.

But also, Utah has the fifth richest bottom quartile of any state, about 40% higher than North Carolina's. So yes, it's much much easier to move from that to the top quartile than in most states.

> The thing is, Utah has never had a truly poor population.

What about when the first destitute pioneers arrived and found a desert?

The Mormon refugees did not find a desert, they found Native Americans living in the Utah Great Basin and proceeded to steal their land and natural resources: http://www.onlinenevada.org/articles/mormons-and-native-amer...

It's not really meaningful to describe people as "rich" or "poor" in the absence of an economy.

Where people are involved there is no such thing as an absence of economy.

At the time (1847), they were not the poorest people in North America.

I'm not sure that achieving a solution is the same as avoiding a problem. And it's not clear to me which has happened.