During our last few lunches, Robin has challenged me to clarify my position on educational signaling – and help my critics to do the same.  And more recently, he named “You have little interest in getting clear on what exactly is the position being argued” as a sign that “[Y]our opinions function more to signal loyalty and ability than to estimate truth.”  Implication: If I clarify what my critics and I are arguing, I raise the probability that I’m a truth-seeker.  Or in other words, I can signal that I’m not signaling about signaling.

Here are the key points of contention as I see them:

1. On average, how much does learning course material causally increase students’ marginal productivity?

My answer: It accounts for roughly 20% of the gross average return to education.

2. At the margin, how much does learning course material causally increase students’ marginal productivity?

My answer: It accounts for roughly 20% of the gross marginal return to education.  The final years of course material are no more or less relevant in the real world than the early or middle years.  Even kindergartens spend a shockingly small fraction of their time teaching reading, writing, math, and other skills that their students will eventually use on the job.

3. On average, how much does schooling causally increase students’ marginal productivity by shaping their character, a la Eliza Doolittle or the Marines?

My answer: Relative to a carefree life of play, this accounts for another 20% of the gross marginal return to education.  But relative to getting a job, the average character-shaping benefit of education is roughly zero.  For very young children with negative marginal productivity on the job, I’ll admit the character-shaping effect is more positive.  But by the time they’re teen-agers, the character-shaping effect is mildly negative relative to employment.  As I told Bill Dickens:

Work inculcates the worker ethos; school inculcates the student ethos. 
The two are only moderately correlated.  The most obvious differences:
Work offers much more tangible rewards for good performance, and much
harsher punishments for bad performance, than almost any school. 
School teaches students the wrong life lessons: Excellence doesn’t lead
to money or status, and disruptiveness won’t get you fired.

Even worse, school often indirectly inculcates counter-productive character traits.  Students spend a lot of their energy trying to show their fellow students that they’re defiant, cool, etc.

4. At the margin, how much does schooling causally increase students’ marginal productivity by shaping their character?

My answer: Mildly negatively.  See above.

5. On average, how much does schooling increase students’ wages by signaling their pre-existing marginal productivity?

My answer: Roughly 80% of the gross average return to education is signaling.

6. At the margin, how much does schooling increase students’ wages by signaling their pre-existing marginal productivity?

My answer: Roughly 80% of the gross marginal return to education is signaling.

7. On average, what fraction of signaling has positive social value because it improves the match between workers and jobs, causally raising workers’ marginal productivity?

My answer: Tough call, but my best guess is 20%.  IQ tests are great, but education also signals other important traits that are too subtle and/or fakeable to easily test.

8. At the margin, what fraction of signaling has positive social value because it
improves the match between workers and jobs, causally raising workers’
marginal productivity?

My answer: Another tough call, but I’ll say 0-5%.  Adding an extra year to a nation’s average education level does little to help employers better distinguish the top 5% of workers from the bottom 5%.

Anyone care to further refine the debate?