Monday, November 14, 2011

Cross sectional reasoning

I want to follow up on a post by Bad Astronomy that has been discussed by both Mark and Noah Smith. The post comments on the results of the 2010 census on employment rates:

I highlighted one in particular: Astronomy and Astrophysics. Note that it has a 0% unemployment rate; in other words, last year everyone who majored in these fields got a job! Now, I find myself being a tad skeptical about this, but if there’s some weird thing going on with this survey, I can at least make the broad assumption that the relative job numbers are probably OK. Majoring in astronomy is still a good idea, and will strengthen your chances of getting a job after college.

I want to take this in a different direction. What this metric shows is that, if you were lucky enough to have majored in Astronomy in 2005 then you were very likely to be employed in 2010. It says nothing about what will happen to somebody who enters the program in 2011 and whether they will be employed in 2015.

See, I was actually a physics major in the mid 1990's, in a school with a large astrophysics group. I knew a lot of these students and even took classes with them. Do you know what they mostly ended up as: High School Teachers. Plus a few academics. At the time there was a terrible job placement rate in physics and we were all depressed by the poor employment outcomes. Using the tool, I see a 4.5% unemployment rate for physics, which does make me wonder how many astrophysicists are counted in this group.

But, in general, past performance is no guarantee of future employment. A depressed job market could easily have led to full employment years later, long after only the most dedicated students remained. I've seen this phenomenon in a lot of fields -- people go where the markets signal but, in education, the signals are lagging indicators.

So maybe we are seeing the unemployment ghettos of the future?

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