What is the cost of educational quality

From The Value of Smarter Teachers: International Evidence on Teacher Cognitive Skills and Student Performance by Eric A. Hanushek, Marc Piopiunik, and Simon Wiederhold. An excellent topic area. From the Abstract:

International differences in teacher quality are commonly hypothesized to be a key determinant of the large international student performance gaps, but lack of consistent quality measures has precluded testing this. We construct country-level measures of teacher cognitive skills using unique assessment data for 31 countries. We find substantial differences in teacher cognitive skills across countries that are strongly related to student performance. Results are supported by fixed-effects estimation exploiting within-country between-subject variation in teacher skills. A series of robustness and placebo tests indicate a systematic influence of teacher skills as distinct from overall differences among countries in the level of cognitive skills. Moreover, observed country variations in teacher cognitive skills are significantly related to differences in women’s access to high-skill occupations outside teaching and to salary premiums for teachers.

Seems well structured and a good-faith effort to get at some important answers. It is handicapped, at a minimum, by its reliance on PISA data which has some well-noted issues.

But perhaps there is enough substance there to at least warrant some confirmation of general assumptions. The implications are interesting.

I have documented in the past that PISA scores are highly correlated with cultural groupings to the continental level at least, and sub-regional in locations such as Europe where there is sufficient data, and in the US where our ethnicity obsession allows a comparison of American PISA scores by cultural heritage (white Americans to Europe, Hispanics to Central and South America, Asian-Americans to Asia, etc.). The notable outcome of that analysis is that, while we bad-mouth our public education system, it delivers superior results when viewed from a cultural heritage perspective. White Americans perform better than all European countries other than Finland (and then only on the reading score), Asian-Americans better than any Asian country, etc. Yes, we have an inordinate number of issues with our public schools, but they are not as bad as is often made out to be.

There are almost innumerable material independent variables which affect educational outcome. A by no means exhaustive list:

Education policy
Centralization versus decentralization
Teacher training
Curriculum
Teacher quality (either years teaching and/or IQ)
Classroom management
Familial structure of students
Socioeconomic status
Per student spending
Class size
Age mixing
Gender mixing
National productivity
Career choices and compensation
Physical context of the school
Cultural valuation of education
Cultural, class, economic, ethnic, religious, etc. class heterogeneity
Relative starting point of children
Relative starting point of teachers
etc.

Disentangling which combination of all those variables has how much affect on which student populations under what circumstances is an enormous question which we have spent fifty years and more trying to understand with some progress but not near as much as we would wish. At this point, it is pretty clearly understood that 1) there are no silver bullets, and 2) one size does not fit all.

Hanushek, Piopiunik, and Wiederhold contribute some useful information.

With both approaches, we consistently find that differences in teacher cognitive skills across countries are strongly associated with international differences in student performance. In terms of magnitude, a one SD increase in teacher cognitive skills is associated with an increase in student performance of 0.10-0.15 SD. Since PISA scores represent the cumulative learning of 15-year-olds, this suggests an average learning gain of about 0.01-0.015 SD per year.

0.15 SD is about 15 IQ points. The implication is that if you lift your average teacher IQ from 100 to 115, you will raise you student performance from 100 to 101.5-102.3.

IQ is distributed on a Gaussian distribution. Only about a third of the population have an IQ above 115. Because it is Gaussian, the further along the curve you got (high and low, the disproportionately fewer there are). At two standard deviations above the mean, there are 3 people above and IQ of 130 (roughly).

Consequently, moving resources from the upper end of the distribution into schools will be tied with a reduction in supply for high cognitive jobs as well as a corresponding increase in cost, representing a loss of productivity.

If what Hanushek, Piopiunik, and Wiederhold have found is true, then the economic question becomes, "Is the loss of supply of 115 individuals for general economic activity more than made up for by increase of general population productivity associated with a move from population average IQ of 100 to 101.5-102.3. I don't know the answer. There are also, of course, all sorts of other ethical and you moral questions as well.

The economic question is hugely pertinent though, especially in a free market environment where individuals are able to make the personal choices that allow them to make decisions which optimize their well-being. If you are living in an agricultural country with low development and poor infrastructure and are out in the rural areas, a job as teacher, even if you are 1 SD above everyone else, might be worthwhile at an average wage because it keeps you close to home. If you are in a developed nation with a free market and are in the city with a 1 SD IQ, it might be the difference between an income of $65,000 as a teacher and $100,000 as a marketing manager. Who makes what choices is constrained by context of location, circumstance, economy, law, policy etc.

And also culture. Some places such as Japan and Finland keep teacher compensation low in return for significant cultural prestige. Te be a teacher is to be a cut above the average in social standing.

We are way too early in our understanding of the metrics, the causal dependencies and the supply elasticity.

My suspicion is that in advanced economies that are highly urbanized and where civil rights are well protected so that everyone has full access to all choices, the cost of pulling in +1 SD teachers will be very high and very apparent and the system return on that investment over a generation will be lower and later and less visible than will make such a shift in resources a compelling proposition at a national level. Local - quite possibly. Nationally - I wonder.