Wednesday, October 31, 2012

Education as Signaling

From Andrei Toom, “A Russian Teacher in America,” Journal of Mathematical Behavior 12 (1993): 117-139.
Suppose you fly in a plane. What is more important for you: the pilot's real competence or his papers that certify he is competent? Or suppose you get sick and need medical treatment. What is more important for you: your doctor's real competence or his diploma? Of course, in every case the real competence is more important.
But last year I met a large group of people whose priorities were exactly the opposite: my students. Not all, but many. Their first priority was to get papers that certify that they are competent rather than to develop real competence. As soon as I started to explain to them something that was a little bit beyond the standard courses, they asked suspiciously: "Will this be on the test?" If I said, "no," they did not listen any more and showed clearly that I was doing something inappropriate.
I had to learn also that American students want to be told exactly from the very beginning of the course what percentage of the total score comes from homework, from tests, and from quizzes. First I thought that it was some nonsense, as if I were requested to predict how many commas and colons I would use in a paper I was going to write. But later I understood that these percentages make sense for those students who do not care about the subject and take a course just to get a grade with minimal learning.
. . . It seems to be generally taken for granted that students nominally learn as little as possible for a certain grade. Only by a misunderstanding may they learn more, and when this happens due to an undetailed syllabus, they blame the teacher like people who blame an official whose neglect caused them a loss.
It is the basic principle of the market that everybody tries to get as much as possible and to pay as little as possible. There is nothing wrong with this: When I buy something, I try to save money, and everybody does the same. What is wrong is that some students apply the same rule to learning: They seem to think that they BUY grades and PAY for them by learning. And they try to PAY as little as possible! In other words, some students seem to think that it is a loss whenever they learn something. This looks crazy when put in such straightforward terms, but there are students who behave as if they think this way.

Tuesday, October 16, 2012

James Kwak on Baumol's Cost Disease

James Kwak writes here about Baumol's cost disease in health care and other industries. Along the way, he makes a point that seems misleading:
Baumol’s argument, somewhat simplified, goes like this: Over time, average productivity in the economy rises. In some industries, automation and technology make productivity rise rapidly, producing higher real wages (because a single person can make a lot more stuff). But by definition, there most be some industries where productivity rises more slowly than the average. The classic example has been live classical music: it takes exactly as many person-hours to play a Mozart quartet today as it did two hundred years ago. You might be able to make a counterargument about the impact of recorded music, but the general point still holds. One widely cited example is education, where class sizes have stayed roughly constant for decades (and many educators think they should be smaller, not larger). Another is health care, where technology has vastly increased the number of possible treatments, but there is no getting around the need for in-person doctors and nurses. The problem is that in those industries with slow productivity growth, real wages also have to rise; otherwise you couldn’t attract people to become classical musicians, teachers, or nurses.
But as Jay Greene points out in this Wall Street Journal piece, real wages for teachers have grown by only 11% over the last 40 years. A more significant reason that K-12 education is more expensive today is that it employs 50% more people:
In 1970, public schools employed 2.06 million teachers, or one for every 22.3 students, according to the U.S. Department of Education's Digest of Education Statistics. In 2012, we have 3.27 million teachers, one for every 15.2 students.

Friday, October 05, 2012

The Null Hypothesis

A good quote to remember:
Research reports in the literature are frequently flawed by conclusions that state or imply that the null hypothesis is true. For example, following the finding that the difference between two sample means is not statistically significant, instead of properly concluding from this failure to reject the null hypothesis that the data do not warrant the conclusion that the population means differ, the writer concludes, at least implicitly, that there is no difference. The latter conclusion is always strictly invalid. Jacob Cohen. 1988. Statistical power analysis for the behavioral sciences. 2d ed. Hillsdale, NJ: Lawrence Erlbaum. p. 16