Mike Konczal slams Steven Levitt
Wow. I kind of had the feeling the new book Superfreakonomics was going to be weak, but I didn’t expect it to look as rough as the preview currently coming. . . .
What I really want to point out is Ezra Klein’s takedown of the opening chapter. Ezra Klein is a health care wonk/reporter/blogger, and he swept-the-leg out of a shoddy econometrics argument by someone who won a Clark Medal for doing econometrics.
The next few pages purport to prove that drunk walking is eight times more dangerous than drunk driving. Here’s how they do it: Surveys show that one out of every 140 miles driven is driven drunk. “There are some 237 million Americans sixteen and older; all told, that’s 43 billion miles walked each year by people of driving age. If we assume that 1 out of every 140 of those miles are walked drunk — the same proportion of miles that are driven drunk — then 307 million miles are walked drunk each year.”
“If we assume.”
But why should we assume that? As the initial example demonstrates, a lot of people walk drunk when they would otherwise drive drunk. That substitution alone suggests that a higher proportion of walking miles are drunk miles. Other people walk, or take transit, when they know they’ll be drinking later. That’s why they’re walking and not driving. That skews the numbers and makes it impossible to simply “assume” parity.
It’s really worth noting that if Levitt was giving this argument at a seminar, and Ezra raised his hand and said what he said, the seminar would be over. Killed.
I think we should start by giving Steven Levitt the doubt for two reasons. One he has done very good work in the past and two civility demands it. We might question why such an assumption was made but Mike is essentially arguing that Levitt has no comeback and we know it. That seems a bit harsh.
Moreover, it seems to me that the obvious reason not to equate drunk driving and drunk walking behavior is that drunk driving is illegal where drunk walking is not. Presumably the law serves as some deterrent.
That having been said I think we want to look at orders of magnitude. Eight times is a good bit. Enough for me to give some weight to the story. Are people Eight times as likely to walk drunk as drive drunk. Maybe. But, that’s the minimum necessary to achieve parity. We would need something like 16 or 32 times more likely to walk drunk in order for it to be obviously safer to walk. That could be true but its not obvious to me that it is true. Thus it really does seem like an open question.
And all of that having been said, my priors would be that drunk walking is more dangerous for the drunk than drunk driving. Basically because the level of intoxication one can be at and still walk is a lot higher than and still drive.
Of course, drunk driving is not a bad idea simply because the drunk my die. Its illegal because the drunk might kill someone else. This seems highly unlikely with drunk walking.