Too much information
May 22, 2012

Don't trust GI Joe--ignorance is half the battle, at least according to the US Preventative Services Taskforce. The task force recommended against screening healthy men for prostate cancer because most of the prostate cancers detected will not kill the patient, and the complications from treatment can be quite severe (impotence, loss of bladder control, etc).

Still, I find the panel's conclusion strange. Couldn't one screen for the cancer, and then just opt out of treatment? How can more information be bad?

Legislating patience
Mar 8, 2012

There is a certain metaphysical point of view, which I associate with Derek Parfit, which holds that you are not the same person as future you. If people are the same as their future selves, the argument goes, then why do current people discount the future-- they procrastinate and reschedule painful appointments for the more distant future.

Suppose that you agree that a person is not the same as his future self. Then should it be illegal for the current person to behave in ways that benefit themselves at the expense of their future selves? Think cigarette smoking. There is an externality argument to be made for taxing cigarettes. If someone else is smoking in the bar I am at, it is bad for my health, and I should be compensated for the additional risk I am taking on. Some of the legislation seems to go beyond this, however. On NPR today I heard a report about legislation aimed at preventing cigarette companies from marketing to children. If someone, say a young adult, chooses to smoke at home, who are they harming? The answer is their future selves. If you agree with the metaphysical position above, then maybe you think that government is correct in correcting a market failure--the harm current people are doing to future people.

Green Inc.
Feb 28, 2012

Alternative energy is closely associated with the green movement in my mind. Greens stand for non-violence, ecology, democracy, and social justice. At the same time, the alternative energy industry has an interest in a high oil price. One thing that drives high oil prices is instability in the middle east. I wonder how wind power executives feel when they hear Iranian officials threaten Israel or civil war erupts in Syria. I plotted crude oil prices vs. the price of GAAEX, an alternative energy index fund. Although recently the two have diverged, the day-to-day jumps track each other pretty closely .

When I mentioned this idea to my officemate Felix, he said that it reminded him of the green paradox of German economist Hans-Werner Sinn. According to Sinn, the expectation of greener energy policy in the future makes the owners of "dirty" energy resources want to extract and burn their reserves more quickly.

How about them apples
Feb 27, 2012

Apple's net profit in the previous quarter was 13 billion dollars. The US GDP is 14.5 trillion dollars a year. Does this mean that Apple created 3/1000 of the value of all goods and services produced in the US last year? (HT: Andrew Gelman)

Eric X. Li went trolling a couple days ago at While I am aware that feeding the troll is against internet protocol, I can't help myself.

1. Straw man: "Why, then, do so many boldly claim they have discovered the ideal political system for all mankind and that its success is forever assured?" Who makes that claim?

2. Who defines "national interest"?: "Its leaders are prepared to allow greater popular participation in political decisions if and when it is conducive to economic development and favorable to the country’s national interest." "The fundamental difference between Washington’s view and Beijing’s is whether political rights are considered God-given and therefore absolute or whether they should be seen as privileges to be negotiated based on the needs and conditions of the nation." What if policies which promote "national interest" hurt many individuals? Who makes up the nation?

3. Crystal ball: "[The Tiananmen Square] uprising was decisively put down on June 4, 1989. The Chinese nation paid a heavy price for that violent event, but the alternatives would have been far worse. The resulting stability ushered in a generation of growth and prosperity that propelled China’s economy to its position as the second largest in the world." What is the counter-factual (Taiwan and Korea seemed to do ok...)? Also, what does "the nation paid a heavy price" mean? The leaders of China came out ok--it was the protestors who were shot on June 4 certainly paid a heavy price.

This year 160,000 people enrolled in a Stanford online artificial intelligence course (HT: Chris Blattman). While those that completed the course received a certificate including their rank in the class, they didn't get any credit from Stanford. Why did so many people enroll?

My own prior is that tertiary education performs three roles: consumption, signaling, and training. Education is consumption because it is fun to learn new things, particularly if those things are presented well. A signaling aspect of college is necessary to explain why employers are willing to pay a large premium for a humanities major over a mere high school graduate. There is training in college as well. After four years of term papers I was able to write down my thoughts without embarrassing myself.

So which apply: Is the Stanford certificate worth something on the labor market, is it fun to learn AI basics from a couple of top researchers, or is there some productive use for the course material?

Scientists: can't find enough subjects for your upcoming experiment? Why not try the opt-out method? Instead of waiting for people to volunteer, automatically enroll everyone in your experiment, and give them the option to volunteer not to be in the experiment. When treating a cardiac arrest victim, paramedics in Seattle will flip a coin to determine which type of care to provide. The only way to opt out, apparently, is to wear a bright red bracelet with the words "no study" printed on it. (ht: David McKenzie)

Do credit card companies know you better than you know yourself?  This article in the Daily Beast (ht: Chris Blattman) reports on the correlations that have been uncovered:

"Data crunching by Canadian Tire, for instance, recently enabled the retailer's credit card business to create psychological profiles of its cardholders that were built upon alarmingly precise correlations. Their findings: Cardholders who purchased carbon-monoxide detectors, premium birdseed, and felt pads for the bottoms of their chair legs rarely missed a payment. On the other hand, those who bought cheap motor oil and visited a Montreal pool bar called "Sharx" were a higher risk. "If you show us what you buy, we can tell you who you are, maybe even better than you know yourself," a former Canadian Tire exec said.

This smells like a kitchen-sink regression to me.  If you do a simple regression of some dependent variable (risk level of credit card user) on a ton of independent variables which have no true relationship with risk (chair pad material, preferred bird seed), some will come out as statistically significant due to random chance.

As a fun little exercise, suppose that we have 1000 observations of credit card users, and we have 500 independent variables relating to purchases which actually have nothing to do with risk.  Suppose that risk varies uniformly from zero to one, and the independent variables relating to purchases which also vary uniformly from zero to one.  I wrote a little matlab program to simulate this situation.  I ran the experiment 100 times, and the median number of statistically significant (95% confidence) independent variables was 25 (surprising, right?).  Since the particular variables which are significant is random, they might be weird things like "number of pepperoni pizzas ordered from Pizza Hut', or 'visits to paid public toilets'.  However, this sort of data would be useless for prediction.

Maybe the credit cards have some more sophisticated tricks up their sleeves, but I am having a hard time relating my love of Montreal pool bars to my credit card payment behavior.

trys = 100;
obs = 1000;
regs = 500;
avg = zeros(trys,1);
for k = 1:trys
dat = rand(obs,regs);
[a,b,c] = regress(dat(:,1),[ones(size(dat,1),1),dat(:,2:end)]);
found = find((b(2:end,1)<0 & b(2:end,2)<0)|(b(2:end,1)>0 & b(2:end,2)>0));
avg(k) = size(found,1);

Jul 6, 2011

Does anyone else see shades of this in this?

Blind Justice
Apr 8, 2011

Dahlia Lithwick's note in Slate about the Obama administration decision to try 9/11 planner Khalid Sheikh Mohammed in a military tribunal is a bit screedy, but generally right on the money:

Today, by ordering a military trial at Guantanamo for 9/11 plotter Khalid Sheikh Mohammed and his co-defendants, Attorney General Eric Holder finally put the Obama administration's stamp on the proposition that some criminals are "too dangerous to have fair trials."
In reversing one of its last principled positions—that American courts are sufficiently nimble, fair, and transparent to try Mohammed and his confederates—the administration surrendered to the bullying, fear-mongering, and demagoguery of those seeking to create two separate kinds of American law. This isn't just about the administration allowing itself to be bullied out of its commitment to the rule of law. It's about the president and his Justice Department conceding that the system of justice in the United States will have multiple tiers—first-class law for some and junk law for others.