It’s so hard to quantify quality. Especially when it comes to education.

At the college level, we try to motivate professors by requiring them to prove themselves in their field of specialization; publish or perish was the traditional phrase.

But at the high school level, we want teachers simply to focus on the kids, and it always will be difficult to evaluate their success.

The Legislature allocated $1 million to study performance-based teacher pay, and over the next two months consultants will ask for public opinion through focus groups, surveys and the like.

One problem is that it’s impossible to talk about one set of salary numbers that fits everywhere in Iowa. More than ever, it’s becoming a state of extremes, as a handful of cities prosper while many small towns struggle.

According to statistics from the Iowa State Education Association, the average teacher salary in Iowa City is $47,362, tops in the state. At the bottom of the list, teachers in Prescott receive an average salary of $27,295.

Does that mean teachers in Iowa City are 74 percent more skilled than those in Prescott? Probably not. Does it mean a good teacher in Prescott watches the job openings in places such as Iowa City? Probably.

And do those numbers mean that the Iowa City teachers are being rewarded directly for their successful efforts – or just that there’s more money to go around in thriving Iowa City than in little Prescott?

Ideally, a school district first identifies its best teachers, then keeps them around as long as possible. But the ISEA statistics also hint that pay isn’t the only thing that keeps them coming back every fall.

In Guttenberg, the pay scale is not bad, ranking 51st in the state. But the average experience within the district is number one at 22.49 years per teacher. So either they stick around because the pay is good, or the pay is good because the teachers like living in that pleasant part of the state and they keep collecting raises … it does get complicated.

Let’s hope the researchers can simplify matters with that $1 million.