## Friday, January 22, 2016

### I'm changing with my mind

 Wikimedia commons.
Since everyone else seems to be doing it, I thought I'd list some things where I changed my mind based on empirical data (as some sort of prior flexibility display). Unfortunately as a physicist, I don't have a lot of economics-relevant items. Actually there is just one:

• I went from believing inflation expectations at the zero bound could raise inflation to seeing that most empirical measures of expectations were backward-looking -- and therefore couldn't be a guide for much of anything in the future. In that sense I drifted from thinking Krugman was right (expectations were possible, but hard for central banks at the zero bound) to Sumner was right (expectations were easy for central banks) to both theories being either untestable and/or inconsistent with empirical data. In a sense, wrestling with this lead directly to this blog.

On most other topics in econ, I haven't formed a strong enough opinion to warrant some kind of adjustment of my priors. I kind of view the subject like I do various statistical health studies -- Drink coffee! Don't drink coffee! I'm not sure where we are on that.

As for physics/science:

• Non-zero cosmological constant. This came out while I was an undergrad and I didn't believe it at first. Since it such a serious fine-tuning problem, I thought it would be zero. More data eventually convinced me that it was a real thing.
• LIGO could successfully measure gravity waves. I used to think this would be impossible, but the papers on the calibration have made me reconsider it. I'm now just ambivalent. It has come up recently in the news and my attitude is wait and see rather than dismissal.
• Placebo effect (warning: picture of surgery at link). It's not that I didn't think it was real -- it's more that I've become more tolerant of "alternative medicines" operating through it ... in fact, a significant fraction of mainstream treatments might operate through it as well.
PS The title is a Mystery Science Theater 3000 reference.

#### 3 comments:

1. Placebo effect: I'm a sometimes reader of this blog:
https://www.sciencebasedmedicine.org/
Steve Novella (one of the contributors there) has talked about this issue. He described an acupuncture study in which the trial subjects were broken up into groups: needles were inserted in the "correct" spots, in the "incorrect" spots, and not actually inserted at all (the needle was depressed behind a sheath and in reality the patient only felt a toothpick pressing on the skin, but not actually penetrating it). The result of this study was that it didn't matter: patients in all groups reported similar benefits. But he pointed out that the acupuncture advocates touted the results as vindication for the efficacy of acupuncture creating a placebo effect! He then asked "Suppose a drug manufacturer did that? A study showed their product was safe and effective at producing a placebo effect (but nothing more)" (paraphrasing). That did seem ridiculous to me, at least in terms of getting any kind of further private or public investment in the drug. What really galls Steve is medical schools or government support of departments that teach or promote alternative medicine, when it doesn't seem they're subject to the same rules as non-alternative medicine. That's my best take on trying to summarize his views. That doesn't necessarily conflict with what you wrote: yes alternative and traditional medicines may indeed operate through it. But what's more ethical: charging somebody 1000s of dollars for a placebo or giving them a $0.01 sugar pill? I guess if the$1000 helps with the psychology, you could argue the former.

BTW, recall your conversation with magpie about Popper and falsifiability? The topic turned to the discovery of Neptune and how that related to the falsifiability of Newton's laws.

It seems like this "9th planet" that's in the news now couldn't have been timed better! I heard a brief interview with one of the discovers on an NPR podcast this morning... describing how he went from playing with a fun idea to actually believing that this planet is likely there. It happened while examining some of the data, and he said his "jaw dropped." Yet rather than keep it secret and try to find it themselves, they put it out there hoping their claim gets lots of scrutiny ... and different teams looking for it as well. It was a nice modern update to that Neptune discussion!

1. I should mention that listening to Steve Novella give a lecture about alternative medicine is exactly the kind of thing I'd do to help me fall asleep, so I think that's where I heard the above... so sorry for a lack of links.

The other night I used that Dani Rodrik lecture you provided a link to for that purpose (sleep aid). It was so effective I remember absolutely nothing of what the man said: I was out like a light! Lol.

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Also, try to avoid the use of dollar signs as they interfere with my setup of mathjax. I left it set up that way because I think this is funny for an economics blog. You can use € or £ instead.