Do credentials = quality?

Just read a 13-page recent history of teacher prep over the last 20 years or so. It's by Arnold Shober, associate professor of government at Lawrence University. He traces a change in thinking:

Equating quality with qualifications was a reasonable assumption before the 1990s as the learning process was not well understood, and an emphasis on training and retaining expertise was appropriate under such circumstances....

But by the late 1990s, it was abundantly clear that this definition was fiction. Teacher qualifications did not guarantee teacher quality....

As late as 1999, Dan Goldhaber and coauthors suggested that 97 percent of teacher quality was “intangible.” For researchers and policymakers, then, identifiable components of good teaching were a mystery.

But the lack of a clear theory of action did not stop policymakers from constructing a causal narrative about what some thought should make a good teacher: improving teacher education and increasing teacher credentials

It's a good paper. Pairs nicely with this Malcolm Gladwell cabernet about predicting who will be successful in football and teaching.