Teacher wages and upward mobility

From David Card, Ciprian Domnisoru, and Lowell Taylor, the last few sentences are the most interesting:

We use 1940 Census data to study the intergenerational transmission of human capital for children born in the 1920s and educated during an era of expanding but unequally  distributed public school resources. Looking at the gains in educational attainment between parents and children, we document lower average mobility rates for blacks than whites, but wide variation across states and counties for both races. We show that schooling choices of white children were highly responsive to the quality of local schools, with bigger effects for the children of less-educated parents. We then narrow our focus to black families in the South, where state-wide minimum teacher salary laws created sharp differences in teacher wages between adjacent counties. These differences had large impacts on schooling attainment, suggesting an important causal role for school quality in mediating upward mobility.

This result is not logically inconsistent with the signalling model, but I think it fits more readily into the human capital story.  If you think employers cannot easily distinguish between different qualities of worker (without the educational signal, that is), probably you also should think employers cannot distinguish among the quality of adjacent schools on the basis of what they pay their teachers in relative terms.  And in that case, the schools hiring the better teachers are probably increasing the productivity of their students.

For the pointer I thank the excellent Samir Varma.


highly responsive to the quality of local schools, with bigger effects for the children of less-educated parents. We then narrow our focus to black families in the South, .... These differences had large impacts on schooling attainment

So, without wanting to download the pdf, the language here is not clear. What is the difference between "highly responsive" when it comes to White children but a "large impact" when it comes to Black children? You might think that better paid teachers improved the quality of education for *all* children, but that is clearly not what they are saying. Or they would have said it. So there is a different impact. Better teachers means better students over all but a greater impact for White student than for Black? Or the other way around.

Do they control for the obvious - middle class children of all colors go to schools in middle class counties and do better at school than poor children?

Blacks had and still have limited mobility in that even with high family incomes, blacks have few choices of where to live, and that determines school and teacher pay. White family mobility is determined by income, and poor, less educated, whites probably had teachers with higher teacher pay than all blacks.

Thus student attainment for whites was sensitive to family status, but for blacks family status had no influence on attainment less than whites, and little difference between blacks.

Can you provide a reliable source for your claim that high income African-Americans have "few choices of where to live"? Oh, and something from this century, please. Or, perhaps, did you mean "have more difficult choices..."? (which isn't the same thing at all, is it?)

If it weren't for "the man" nearly all of them would be valedictorians, Medal of Honor winners, or Nobel laureates.

...and THAT'S why I come here. (Aside from the pretty "huge" question of how a study looking at two seemingly very different things be allowed to pass peer review...) How did (do?) state minimum-wage laws increase the difference between adjacent (?) counties? (In adjacent states, perhaps? but if so, there are many more things (like state licensing, state taxes, property taxes, etc. etc.) that you'd need to account for, isn't there?) Confused again, sigh.

And I've gotta say, aside from historical interest, how do kids in school (Grades 1-12, since I don't think K wasn't a thing in the 1920's) and the impact of various factors in their mobility as of 1940...(why would we expect teenagers to have ANY significant "mobility"??) say anything about the factors plaguing today's fubar public education systems?

typo = don't think Kindergarten was a thing

I assume (perhaps incorrectly) what they were trying to say was that the teachers salaries were state minimum + a potential local increment, where the local increment could be material; and that those difference would be reflected in teacher quality.

In the area where I grew up in the 50's and 60's, some school districts were well known for the high pay and noticeably better facilities, due to having one or more plants in the district that provided a very large local tax base. That's is still the case to a lesser extent.

So in a poorer area, pay would be the state minimum, and only attract the weaker teachers, while in other wealthier areas, the could afford a better quality of teachers.

This means that minimum salary laws tend to *reduce* variance, not amplify it.

The statement about state-wide minimum wages laws for teachers causing county differences struck me as odd too. My guess is that the wealthier counties would pay teachers more than the minimum to attract the best teachers. But that doesn't make much sense, because the wealthier counties can pay teachers more whether or not there is a minimum wage law for teachers (i.e., the minimum wage law doesn't "cause" the salary differences).

I think it refers to counties of one state adjacent to counties of another state.

We show that schooling choices of white children were highly responsive to the quality of local schools

The "quality" of local schools is determined by the melanin content of the students' skin, since there is no other reliable method of evaluation for making such a choice.

Sorry, but nobody here understands this paper (I'm talking about everybody upstream not just Engineer). I'm on a limited bandwidth connection here in remote Philippines, so I can't read the paper, but the key is this TC quote: "This result is not logically inconsistent with the signalling model, but I think it fits more readily into the human capital story." - in other words, the study supports BOTH signaling (that is, education is meaningless and the smarter students are just showing off by going to school), AND non-signaling, 'human capital' (i.e., schooling improves students, regardless of their innate IQ).

BTW, this same duality shows up in how society rewards inventors. Do inventors just invent, regardless of incentives (that's the traditional model, practiced today, thus no need to improve incentives via better patent law), or, do inventors respond to incentives, and thus can innovation be engineered or taught?

If I were the conspiracy-minded type, I might view the obsession by some with the signaling model as a rationalization for not providing equal educational opportunities for the not wealthy, equal in the sense of providing public support for the not wealthy to attend the best (elite) schools: what's the point of attending the best (elite) school if it's just signaling rather than a quality (best) education. Some people will believe anything if it's framed as anti-elitism. But I'm not the conspiracy-minded type so signaling it is; and our best students might as well attend Southern New Hampshire University rather than Harvard, Yale, Princeton, MIT, Chicago, Berkley, Stanford, Michigan, or UVA.

Not everyone can attend the “elite” schools. Doesn’t mean that we can’t set a reasonable minimum standard for all; at least with teachers who can read, civil behavior standards, working heaters, etc. Some people would say it includes sports complexes that colleges a generation ago would envy.

One of the virtues of local control is the voters can decide these things. I routinely vote for school bonds. I vote for the school board as well, but the district is so large now it doesn’t mean much.

I have talked to several teachers in private day schools in Britain. They don't in general get paid more than equivalents in State schools. But they do get to teach much better pupils - brighter, better behaved, more interested in their lessons.. That's where the main reward comes, apparently.

Even among Americans surely non-financial rewards count for something.

Wow. Its fun to impute causation. Higher pay causes better teaching. Better teaching causes upward mobility. I guess teachers really are the center of the policy universe.

Edgar, If you live where you don't have children in school (because you are retired) or have your kids in private school, you don't vote to support public school funding. If you live where most of the kids in public schools are minorities and you send your kids to private schools, you don't vote to support public school funding.

Retired guy here, and as noted above I routinely vote for public school bonds. I also vote for school board who sets the tax rate for the district. I get a bill every year explicitly for school taxes. It’s the largest line item on the tax bill.

I’ll admit that the public schools are slowly depleting my originally quite deep reservoir of good will.

I'm glad you do. At the time someone who did not have kids in school voted to support your kids, and now its your turn.

Life cycle voting.

When you vote for school bonds, you're voting for parents rather than children. You're giving parents a free babysitting service but you're not doing children any favors. If someone voted to incarcerate you in a school 30 years ago, that doesn't mean you should vote to incarcerate children today. Maybe parents should pay their own babysitters.

Do really believe what you are saying?

I believe what he is saying.

I am not surprised.

"Higher pay causes better teaching".

I don't think that is the take-away. Imagine being a school superintendant in County A where the minimum teacher salary is, say, 30 percent higher than in adjacent County B (in the same or different state). I doubt it would be that difficult to poach the "better" teachers from County B. The teacher would likely not even have to move to take the new job. The result may likely be that the instruction and outcomes show an improvement in County A. But what about County B? I don't think the study shows absoulte outcomes for the two, but relative outcomes. What is the absoulte outcome of all this for County A *and* County B? To my knowledge, the study says nothing about overall rather than merely relative outcomes.

Another possible factor, which has nothing to do with the absolute level of teacher salaries, is that motivated parents might be inclined to move their children to County A schools. The disparity of pay might well have good effects for County A schools but just the opposite for County B.

In order to show that higher County A salaries improve overall outcomes, it seems to me the authors would need to show something of the following:

1. The higher salaries motivated teachers to do a better job;
2. The higher salaries motivated more qualified persons to enter into the teaching profession.

I don't think the study does anything to prove either.

Why do education researchers NEVER (or: so seldom) consider the metrics that could be fashioned to measure--however accurately--the actual rates of literacy attained by public school graduates since, oh say, 1950?

Why, for that matter, are we never told by the custodians of the US public education shambles just how many employed teachers, principals, guidance counselors, coaches, band directors, administrative staff, et al., perform their duties while sub-literate or functionally illiterate?

When do Card, Domnisoru, and Taylor devise working metrics to measure adult literacy attainments effected by US public schools for all graduates since 1950?

When might ANYONE discover and publish the magickal equations that could yield these elusive data?

Et cetera, et cetera, et cetera (do note the item below the posted link for the literacy lawsuit story: even though the lawsuit [alleging illiteracy as an outcome of exposure to public education] has been dismissed, two thousand Detroit teachers nevertheless are eligible for deferred compensation and "performance bonuses"):


Is it overly cynical of me to assume there's simply a lot of p hacking in the paper? They could just look at student attainment by country teacher salary across the board, but instead they look at black students in the south, and only states with minimum wage laws and compare only adjacent counties with salary gaps. It just sounds like they couldn't find the results they wanted in the data, and started slicing different cross sections until they found it. A theory that's not inconsistent with the human capital model, but fits better with the replication crisis story.

I meant county, not country, obviously.

Good point.

People do county side by side comparisons all the time. If you can dispute the data, rather than call it p-hacking, do it; otherwise you are just responding because you do not like the results.

You should read the last section of the paper, rather than the summary.

I've always hated ambiguous statements in abstracts, like this one "These differences had large impacts on schooling attainment, suggesting an important causal role for school quality in mediating upward mobility." Okay, so in what direction was the impact of statewide teacher salary minimums? You can't tell from that statement. It could be positive because the district now attracts higher quality teachers (speculative) or lower because now districts can't afford as many teachers and class size increases accordingly. Just say what you want people to know.

It is always good to read the paper.

Here is part of it in the conclusion section:

"Our work shows that there were important consequences of inequalities in public school- ing in the U.S., especially disparities due to racial segregation in education. In many Southern states, black public school teachers earned less than half of what white teachers earned—a disparity that is all the more striking given that white teachers in the South were relatively poorly paid. In 1940 a substantial majority of black children were educated in the South, and thus the median black child lived in a state in which the cost-of-living ad- justed salary of black teachers was only $649 (in Virginia), while the corresponding median white student had a teacher with cost-of-living adjusted salary of $1727 (in Wisconsin).52 Taking our baseline IV estimate for black children at face value (0.32 from row 1 of Ta- ble 8), this gap translates to a disadvantage in completed schooling of approximately 3.4 years. Assuming a 7% return to each year of education, an increase in resources allocated to the median black child (to the median level of white children) would have resulted in 25% higher earnings per year of work. But this calculation may well understate the dis- advantage to black cohorts born in the 1920s because, as Card and Krueger (1992a) show, low schooling quality also reduces the return to schooling. A rough calculation that incor- porates their estimate suggests that our counter-factual increase in schooling quality for black students might have increased annual earnings by well over 33%.53"

Honestly... that passage is not that is also poorly written (the first sentence could be deleted and I bet you could cut out 50 words without losing any meaning). I agree that one should read the paper if time permits, but academic writing is so atrocious that a researcher could help himself out be clearly stating the research question and the results in the abstract. My point was that the abstract was terribly written (I knew what the results were from reading Tyler's comments), and being unable to tell what the conclusion/results of the paper are from the abstract that doesn't entice me to actually read the paper. Number 1 rule for presenting research: make it easy for the reader.

Here is what they wrote on page 27: "In summary, our analysis shows that policies that increased teacher salaries substantially improved upward mobility in education among black children in the South in 1940."

Now that is clearly written, no "important consequences" or "large impacts... suggesting a causal role" ambiguity. It would be much better if they put that statement in the abstract.

Should we distrust Card and lower his status on this inasmuch as he is using statistics in a tortured way to justify Harvard's obvious abuse of Asian applicants? What other agendas are determing how he has chosen to frame this material and its results? What other tests has he NOT run because of this?

You offer no evidence and simply try to discredit someone because you disagree.

Card has no defense to the problem that Asian students interviewed by alums and given the same ratings as comparable white students for personality were mysteriously downrated by the admissions committees which often had not met the candidates.

He uses tortured controls for address and schools -- which often proxy for race -- and then says that controlling for these factors, Asians don't do so badly. That's like saying, ignoring race, race doesn't matter.

I read Card's expert report as well as the reply by the opposing expert. First, what you say is not what the report says. Second, even the opposing expert doesn't say what you say, even though he would have had an incentive to say so.

So, your comment is just unfounded and unsupported.

It would be very interesting to study whether better teachers migrate over their careers toward schools with higher pay or with smarter / more cooperative students.

For example, within giant school districts, teachers tend as they get more experience to either move to schools with better students or, while staying within one school, toward classes with better students.

There are numerous programs to pay teachers more to teach bad students. Economists should study how big this tradeoff would have to be and how much good does it do to have better teachers teaching lower capacity students. It used to be a truism that it was a good thing Socrates had Plato as a student and Plato had Aristotle as a student, but today's Conventional Wisdom is that all three should have been assigned to tough schools down by the docks.

"Why, for that matter, are we never told by the custodians of the US public education shambles just how many employed teachers, principals, guidance counselors, coaches, band directors, administrative staff, et al., perform their duties while sub-literate or functionally illiterate?"

We are told. And the answer is none, although we may get a few in the future since there's a push to increase minority teachers via loosening the credentialing standards. We have dramatically increased the standards for elementary and middle school teachers over the last 20 years. The standards for high school academic teachers have already been high.

And remember, we have a teacher shortage.

"Even among Americans surely non-financial rewards count for something."

Not really. Private schools have tremendous staffing shortages, and often end up going a year or more using subs. Public school teachers who want to upgrade their students switch schools, but don't go private.

Most people who know very little about education in US assume that public school teachers are just dying to move to charter or private schools, when in fact charters hemorrhage teachers to publics and private schools have turnover rates far worse than your average urban public school.

"For example, within giant school districts, teachers tend as they get more experience to either move to schools with better students or, while staying within one school, toward classes with better students."

Not as much as you might think. I used to think that, but new teachers tend to get lower level classes because the math is more familiar and the students are more familiar with the material, there are more mentors, and so on. And as I mentioned above, turnover at all but the very worst, high poverty urban schools is fairly low.

There is quite a bit of research on the tradeoffs needed. What the last study showed --and I'm doing this from memory--is that a huge effort to convince high quality teachers to change schools for significant money ($10K/year) got a fairly small percentage buyin, and the teachers who switched schools were the ones who were working in not-quite-high-enough poverty schools. So say the offer was for $10K to convince teachers to work in schools with over 50% poverty, then a lot of the responders were teachers at schools with 45% poverty. The teachers from 10% poverty schools mostly passed.

As I understand it, the research is saying that the payout has to be amazingly high, like 30% boost to get teachers to work in high poverty schools--and I'm assuming, again from the writeups I've read, that the high poverty schools were like mine--suburban, basically well-behaved, just lower skills and motivation. You couldn't pay me enough to go work in a high poverty urban high school.

The easiest way for a teacher to make more money, in this era of shortage, is to work through prep. In most states, that's a 20% boost minumum. Why switch schools if you can do that?

Finally, remember that there are many, many different things we call "teaching", and the teachers that get good results in low poverty schools would be likely crushed into bloody pulp at a high poverty school. It's simply not the same job.

"And in that case, the schools hiring the better teachers are probably increasing the productivity of their students."

There's no absolute "better" teacher.

"And in that case, a school with a particularly SES profile hiring teachers that more effectively instruct and motivate students typical of that profile is probably increasing the productivity of the students with that profile."

But if we start admitting that some students need different sorts of teaching, we'll get lawsuits, not increased productivity.

A general problem with these kinds of studies is they conflate "mobility" with "movement." An ordinary potato has neither, a couch potato has the former but lacks the latter.

It's always getting less difficult to move from the lowest income quintile to the highest in America, but on the other hand there's ever less motivation to do so, given the ever-increasing abundance of food, shelter, and cheap diversion since the beginning of the Industrial Revolution. Even in the 1920s, society was pretty far from the status-obsessed Pride and Prejudice of a century earlier in which you who married had a large effect on circumstance as basic as your expected caloric intake and access to clean water.

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