Charlatan!

My two least favourite "public intellectuals" are Niall Ferguson and Nassim Taleb. I've posted several times in response to things that Ferguson has written. After an listening to an excruciating interview with Taleb on the otherwise wonderful Planet Money podcast, I wanted to post a grand critique of Taleb to try to debunk the idea that hes' some kind of "deep thinker." Since nobody cares and I actually have real work I ought to be doing, I was very pleased to find this blog post which nails Taleb quite effectively.

Taleb is merely setting himself up as some sort of heretical alpha monkey of the quants for stating the obvious, the misleading, and occasionally the gratuitously wrong-headed and untrue.

I have no idea what an "alpha monkey of the quants" might mean, though I do like the sound of it. But if you listen to the Planet Money interview, you will see what Locklin (the blogger) means in the rest of the sentence.

Locklin also quotes Taleb as saying " Our research shows that economic papers that rely on mathematics are not scientifically valid." This might be obvious, if "rely on mathematics" means excluding any form of evidence. For example: Edward Wilson defines science as the "systematic enterprise of gathering knowledge about the world and organizing and condensing that knowledge into testable laws and theories." So math without reference to knowledge of the world is not science. It's math. But if "rely on" means to use as a necessary part, then this quote falls into the category of "gratuitously wrong-headed and untrue." Locklin has a great response:

I agree that many economics papers are silly. Since economic papers often involve math, his reasoning seems to be something along the lines of “we must do away with mathematics and instead base economic policy on chicken entrails and pixie dust.”

The Parallel Universe Machine

If you're not sure what you think of the $800 bn Obama stimulus, then this is the podcast for you to listen to. Two caveats. First, there may not be anyone who is not sure what they think. Among the people paying attention, I get the impression that everyone is pretty much 100% sure it was a big waste or money or the only thing that kept us from entering another great depression. Second, the podcast is far from conclusive. But at least you get a sense of why we should feel unsure.

The key idea is that as scientists we would like to use the stimulus as an experiment to see if Keynes was right. But quickly we realize that it's a crummy experiment because there's no control group. We need a parallel universe in which everything else was the same but the stimulus was not enacted. But the commentators point out that economists have "parallel universe machines." We use estimated models to conduct counterfactuals. If the model is right, we can say what the parallel universe would look like. According to Mark Zandy, unemployment would be 11.5% instead of 9.5%.

The Planet Money reporters rightly point out we should be skeptical about these models. But they don't get the reason right. They seem to think it's because the world keeps changing so the laws don't stay fixed long enough to figure them out. I don't accept that premise. Rather,the basic problem is that the estimates in the model were created by regressions that lacked a parallel universe. So they use observed time-series and cross-section variation instead. In some cases--my own work, for example ;-) --we can get estimates we trust this way. But for economic stimulus, the problems of holding all else equal in other periods or other places just seem insuperable. Not wanting to end on a pessimistic note, I actually got something really helpful from this podcast: a new metaphor for what I do at work. I'm a builder and operator of parallel universe machines!

Why so slow to recover?

The US economy doesn't look very good these days. What happened to the recovery that seemed to be moving at a pretty good clip last spring? Here are four theories I've been hearing.

1. It's the Greeks. According to this idea, Greece's sovereign debt problems are creating uncertainty and fear. I'm skeptical. In the past far more important economies have had just as big problems without a notable drag on the US economy (Mexico in 94' , Brazil and Russia in 99', most of Asia in '97). So how did we shrug those disasters off but not this one?
2. It's the debt. This is the idea favoured by fiscal conservatives. The idea is that the US government has spent beyond its means and everyone now recognizes that a day of reckoning approacheth. Thus we save now so we can afford to pay our taxes down the road. Yeah, maybe.
3. End of stimulus. The government boosted demand but now that the stimulus is drawing to a close; we would need the private sector to replace falling government demand with rising consumption and investment. But they're not in the mood. Why not? See 1,2, or 4.
4. Deleveraging sucks. Debt was high relative to asset values and asset values were inflated. So debt was really, really high relative to fundamentals. Now that debt has to come down and there's no easy or fast way to do it. This is the theory that makes the most sense to me. It is complementary with theory #3.