One can often hear the argument that if teaching is an underpaid and unappreciated profession (which it arguably is), then the best potential teachers will simply opt to pursue another career. This may then take its toll on our children.
Considering that most teachers are women, and that women’s average annual income rose by 50% from 1985 to 2000, while real wages in education only increased 15%, it is indeed a concern that the best may not choose teaching as a profession. This would be quite unfortunate because teacher ability has been linked to student ability in various studies. This post examines trends in teacher ability.
Richey (2014) compares two cohorts: one that started teaching between 1982 to 1995 (birth years 1957-1964), and one that starting teaching between 2001 and 2010 (birth years 1980-1984). He uses results on a standardized test that is corrected to make the results of the two cohorts directly comparable. This is a first in the literature. Previous papers seem to support the hypothesis that teacher ability declined somewhat, but they did not have access to test scores that are directly comparable across cohorts.
First, the author compares the test scores of each cohort for the full sample, and breaking it down by quantile. The results suggest that there was no change in teacher ability. While scores may have declined, the effect is not significant with the exception of a small but significant drop at the 75th percentile.
What is more interesting is when the data is broken down into demographic groups. Richey (2014) finds that white women teachers had a significant drop in their ability over time. But then why does the full sample not exhibit this change? Because it was offset by another big demographic group: minority women. Minority women teachers had a great increase in their abilities over time, offsetting the drop in white women’s abilities, thus leaving the combined average relatively unchanged. Men teachers’ ability stagnated.
The three graphs below show these effects visually. They depict the ability distribution of the older (1979, solid line) and the younger (1997, dashed/dotted line) cohort. The first figure is for the full sample, notice a small drop in the peak of the distribution, and a small shift to the left. This effect indicates a drop in ability, however, it is not significant. The second figure shows the same distribution for white women only. There is a similarly small drop in the peak, but a much larger shift to the left. The third figure is for minority women showcasing an amazing increase in the peak, and a huge shift to the right.
The author also tried restricting the sample to only those people who had been teachers for at least 2 years at the time of the survey. This is to control for attrition. I.e. it is a concern that there is high attrition in the teaching profession because of low pay (and perhaps other factors). Thus it might be that young high ability teachers quickly leave the profession, and they might bias the ability in the full sample upwards. Excluding them from the sample, and concentrating only on (relatively) experienced teachers who are more likely to stay in the profession, however, does not change the results much.
Secondly, Richey (2014) also looks at within cohort variation. I.e. are there any trends within each cohort? The data show that within the older cohort there is some decline in ability over time, which seems to affect all demographic groups and quantiles relatively equally. Thus it appears there was some decline in teacher ability during the 80s.
Is there a similar trend in the younger sample? Not really. This sample doesn’t show any clear trend. And since we just established that (for the full samples) there was no difference in abilities between the older and younger samples, we can deduce that if there was indeed a decline in teacher ability in the 80s, there must have been somewhat of a rebound in ability during the 90s. This is why the two cohorts do not appear different in terms of abilities.
Finally, the author examines whether the ability of teachers in each cohort relative to the ability of non-teachers (i.e. those who chose another profession) of the same cohort has changed. In other words, are relatively lower ability people becoming teachers today than in the past?
Confirming the previous results, for the full sample no such trends seem to exist. The ability of teachers compared to non-teachers did not change. Demographic group level analysis confirms previous results as well. For white women, the ability gap between teachers and non-teachers decreased by about 50%. For minority women, it increased by a huge amount, about 125%. (Note that, in general as well as for each demographic subgroup teachers have higher abilities than non-teachers. Thus a decreasing ability gap means losing ground relative to non-teachers. Consequently, an increasing gap means a rising advantage over non-teachers.)
So in sum, there is no downward trend in teacher abilities despite what some may have thought. This might give the impression that not much is changing in the teaching profession ability-wise. However, this could not be further from the truth. The full sample data simply conceals the huge changes that are going on within certain demographic subgroups. White women teacher abilities are declining, and minority women teacher abilities are on the rise. It would be important to pay attention to these trends, and study what causes each of these subcases. It appears for the time being that minority teachers saved our schools from a rapid ability decline. But how long can whatever causes this last? When will the increase in minority teacher abilities plateau? Will it then follow the downward trend of white teachers? Lots of things to be studied here with potentially important policy implications.