Monday, October 30, 2006

Massachusetts Vehicle License Applications Offer a "Freakonomics" Data Set Opportunity

My Massachusetts drivers license expires next February. Looking over my application for a new license, I see that I am asked to report my current zip code, my sex, my social-security number, my age and whether I have had a sex change. The question asks "Check here if sex designation has changed. Change sex designation to Male, Female"

How could a creative economist use this data, if she had a representative sample of say 10 million data points? Let's suppose that this researcher used the social security number to merge IRS tax data to this drivers' license application.

1. One could study the relationship between having a sex change and personal income. I would presume that richer people are more likely to have a sex change but I don't know how much of a subsidy the state provides. If the IRS offered several years of tax returns, do incomes rise for women who become men? Even if you couldn't merge this data to the IRS data, you could use average zip code income levels to crudely test some hypotheses.

2. After a sex change, do people move from "conservative" zip codes (based on voting percentages in the 2004 election for Bush) to "liberal" zip codes? Or do people who live in such conservative communities, never have sex changes?

3. At what age are sex changes most likely to take place?

4. Do tall men avoid having sex changes (all else equal)?

I'm not sure what would be the public policy implications of this study but I have a feeling that people would want to know the answers to these questions.

On second thought there is one final question here on the license application that has public policy implications.

"Do You want to be an organ donor?"

5. I would use this information to test some altruism hypotheses. Are richer people more likely to be organ donors? Are people who live in "liberal" zip codes more likely to organ donors?