Economist: Although average hourly wages vary considerably between different regions of this country, in each region, the average hourly wage for full-time jobs increased last year.
Given that ...
In every region of the country, the average hourly wage for full-time jobs increased last year.
How is it that ...
In the country as a whole, the average hourly wage for full-time jobs decreased last year?
Evaluate
This is a tricky mathematical paradox. If the average wage went up in each region, then how could the average wage go down nationally?
Normally, we don't spend too much time up front on Paradox questions trying to guess the answer because there could potentially be a lot of ways to resolve the Paradox. But when it's mathematical, there is often only one way.
In this case, in order for every region's average to go up while the national average went down, we need there to be a net effect of people moving out of regions whose average is higher than the national average into areas whose average is lower than the national average.
Say that the average wage nationally is $25 / hr. Some regions, like San Francisco, will have regional average wage of $30 / hr. Some regions like, like Oklahoma City, will have a regional average wage of $20 / hr.
Let's say, last year, OKC's average rose to $21 / hr and SF's average rose to $31 / hr.
We'd expect the national average to start creeping towards $26 / hr. But now consider the effect if tons of people move from SF to OKC.
Someone who used to be making $30 / hr in SF now lives in Austin and makes $21 / hr.
When it comes to the national average hourly wage, people who made $30 / hr last year but make $21 / hr this year are going to bring that average down.
Or in case this makes more sense, suppose that SF is a region with a $30 / hr average wage. OKC is a region with a $20 / hr average wage. Bob lives in SF and makes $28 / hr.
Now he moves to OKC and makes $25 / hr. What has he done to the average wage in SF, OKC, and nationally?
He raised the average wage in SF, because if the average is 30 and you get rid of a data point that is 28, then that will boost the average. (If you kick a teenager off your team, then the average age of your team will go up).
He raised the average wage in OKC, because the average there was $20, but he makes $25. And he lowered the national average, because he went from making $28 to $25.
Goal
We need to hear that people moved out of higher paying areas into lower paying areas.