Galton’s Bayesian Machine
Stephen Stigler has a cool piece on a machine that Francis Galton built in 1877 that calculated a posterior distribution from a prior and a likelihood function. Galton's originality continues to astound.
Here is Stigler:
The machine is reproduced in Figure 1 from the original publication. It depicts the fundamental calculation of Bayesian inference: the determination of a posterior distribution from a prior distribution and a likelihood function. Look carefully at the picture–notice it shows the upper portion as three-dimensional, with a glass front and a depth of about four inches. There are cardboard dividers to keep the beads from settling into a flat pattern, and the drawing exaggerates the smoothness of the heap from left to right, something like a normal curve. We could think of the top layer as showing the prior distribution p(θ) as a population of beads representing, say, potential values for θ, from low (left) to high (right)….
…the beads fall to the next lower level. On that second level, you can see what is intended to be a vertical screen, or wall, that is close to the glass front at both the left and the right, but recedes to the rear in the middle.
…The way the machine works its magic is that those beads to the front of the screen are retained as shown; those falling behind are rejected and discarded. (You might think of this stage as doing rejection sampling from the upper stage.)
…The final stage turns this into a standard histogram: The second support platform is removed by pulling to the right on its knob, and the beads fall to a slanted platform immediately below, rolling then to the lowest level, where the depth is again uniform–about one inch deep from the glass in front. This simply rescales the retained beads… the magic of the machine is that this lowest level is proportional to the posterior distribution!
Hat tip: The Endeavour.
War
KABUL, Afghanistan–Nine boys collecting firewood to heat their homes in the eastern Afghanistan mountains were killed by NATO helicopter gunners who mistook them for insurgents, according to a statement on Wednesday by NATO, which apologized for the mistake.
How would you feel if foreign helicopters periodically rained hellfire on your children?
Sentences of the Day
Michael Kinsley on Movie Math.
Richardson says that the film and TV subsidy has brought "nearly $4 billion into our economy over eight years" and has created 10,000 jobs. By "our," he means New Mexico. He says every state should emulate this success.
I do hope MR readers will find this amusing.
Globalization and the Expanding Moral Circle
In 1869 the Irish historian William Lecky (1838-1903) wrote that moral progress is about extending the moral circle.
At one time the benevolent affections embrace merely the family, soon the circle expanding includes first a class, then a nation, then a coalition of nations, then all humanity…
What is the effect of globalization on the moral circle? Does trade melt barriers and expand the moral circle or does globalization make "the other" a more salient division allowing politicians to demonize and control through xenophobia?
Two pieces of evidence, one anecdotal the other experimental, suggests that globalization expands the moral circle. The anecdotal evidence is the cover story of this month's Wired titled "1 Million Workers. 90 Million iPhones. 17 Suicides. This is where your gadgets come from? Should you care?"
Now from a rational point of view this is absurd. Put aside that the suicide rate is higher among American college students than Chinese workers at Foxconn, even odder is that the writer cares about 17 suicides but not say the million plus deaths in China due to lung disease. But no one said that the moral circle grows for rational reasons. In this case, the writer, Joel Johnson, found that the purchase of the cell phone extended his moral circle to workers who assembled the phone half a world away:
I was burdened by what felt like an outsize provision of guilt–an existential buyer’s remorse for civilization itself. I am here because I want to know: Did my iPhone kill 17 people?
What about the experimental evidence? In an excellent paper, Buchan et al. discuss results from a public good dilemma game that they ran on thousands of people in six countries around the world: Iran, South Africa, Argentina, Russia, Italy and the United States.
In each country the players could contribute to themselves, to a local group or to a world group. Local contributions were doubled and world contributions were tripled such that the world-group maximizing strategy would be for all contributions to go to the world account, the local-group maximizing strategy would be for all contributions to go to the local account and (as usual) the dominant strategy was to contribute to self only. (Local contributions also paid more to self than did contributions to the world account).
The authors find two strong effects. First, the rate of donation to the world account increased significantly with the extent of a country's globalization, as measured by a globalization index. Second, within countries the rate of donation to the world acount increased with an individual's globalization index (based on measures such as whether the individual worked for an international firm, watched foreign movies, called people abroad etc.) Thus, globalization increases the potential for global cooperation.
The authors conclude:
…not only is living in a more globalized country associated with more cooperation at the world level, but the same relationship holds as the degree of individual global connectedness increases as well. The cosmopolitan hypothesis receives clear support from our experiments.
… our findings suggest that humans' basic “tribal social instincts” may be highly malleable to the influence of the processes of connectedness embedded in globalization.
School Report Cards Work
Simon Burgess, Deborah Wilson and Jack Worth look at what happened after school report card were abolished in Wales.
We test the hypothesis that the publication of school performance tables raises school effectiveness. Our data allow us to implement a classic difference-in-difference analysis comparing outcomes in England and Wales, before and after the abolition of the tables in Wales. We find significant and robust evidence that this reform markedly reduced school effectiveness in Wales. There is significant heterogeneity across schools: schools in the top quartile of the league tables show no effect. We also test whether the reform reduced school segregation in Wales, and find no systematic significant impact on either sorting by ability or by socioeconomic status.
Hat tip: Economic Logician who also notes this study on report cards in the Netherlands.
Genetic Factors and the Religious Life
It's getting late but for the record you can find a good study of genetics and religion in Do Genetic Factors Influence Religious Life? Findings from a Behavior Genetic Analysis of Twin Siblings. PSYDIR offers a good summary:
It's a fairly standard twin study. They took a sample of around 600 identical and non-identical twins from the National Survey of Midlife Development in the United States (MIDUS), and looked at a number of religious characteristics.
Basically, their analysis allows them to tease out the variations that are shared by identical twins but not by non-identical ones (genetic factors), by non-identical twins (family factors or shared environment), and that differed even among non-identical twins. This last factor was put down to the effects of external environment (i.e. things that happen in you life that aren't shared by your twin).
I've put the results in the graph. First off, look at childhood religiosity. The biggest factor is your family, and not your genetics. It's not until adulthood that the effects of genetics really start to shine through. No surprises there!
The 'salience', or importance of religion in your life is about one-quarter defined by genetics, as is your spirituality. The most important factor here, however, is the external environment. You get similar results for religious attendance.
When you get to more personal beliefs, the patterns start to shift. There are three factors that are about 40% driven by genetics, with your family upbringing having hardly any effect. These factors are: how often you turn to religion for guidance, whether or not you take the bible literally, and whether people should stick to one faith, or experiment with others (exclusivist beliefs).
It is true that there are tricky statistical issues with twin research and it is certainly possible that results like these will be overturned in the future. If that happens, however, it will be because of better twin/adoption and direct genetic studies. The type of evidence that Tyler cites is simply not capable of answering the fundamental questions that are being asked by this type of research. It is also true that these results are conditional on an environment, that is a time and place. (But that is the relevant measure for parenting today.)
I would also note that if you think the statistics get the numbers wrong you also have to deal with the fact that the patterns make sense. Parents have the biggest influence on childhood religiosity, non-shared environment has the biggest influence on attendance, genetics has the biggest influence on being "born-again." (Even the word suggests nature.) Bryan's book reviews a number of studies like this which are broadly similar.
Parenting: Anecdotes and Data
Tyler's post, What Can Parents Influence (below), uses anecdotes from his own family to try to rebut some findings from behavioural genetics. I don't think the rebuttal is successful. Moreover, Tyler's anecdotes are selective. A fuller description suggests a more balanced accounting of nurture and nature.
Yes, Yana speaks Russian which she learned from her mother. Yana also speaks French, German, Spanish and I believe several other languages. Tyler tells me that Yana has a gift for languages. Tyler also does not mention that his wonderful wife, Natasha, doesn't simply speak Russian she is an accomplished translator. Perhaps the gift runs in families?
But enough of anecdotes. On religion, I don't think Tyler has fully confronted the evidence from genetic studies. Of course, a child born to Orthodox parents is more likely to practice and be Orthodox. EVERYONE agrees with this. So how can Bryan say parents "have little long-run effect on intrinsic religiosity or observance"? Parents with blue eyes often have children with blue eyes but parents don't have much influence on whether their children have blue eyes.
More fundamentally, what Bryan is asking is how much does parenting influence religiosity? To answer this question we have to distinguish parenting from parents. How do we do this? Adoption and separated twin studies. What adoption and separated twin studies show is that once you have controlled for parents, parenting has very little influence on adult religiosity. These studies could be wrong but, contra Tyler, stamping your feet is not good enough on this issue because what we naturally observe (primarily parents raising their biological children) is not what we need to know to answer the fundamental question.
I could say more but instead let me say this, buy Bryan Caplan's book Selfish Reasons to Have More Kids. It's a remarkable book. I place it alongside Guns, Germs, Steel and The Selfish Gene as one of those books that, whether one agrees with the conclusions or not, everyone owes it to themselves to read in order to be informed, educated, and part of the conversation.
Libya Dissertation Fact of the Day
From a 2007 PhD Dissertation awarded by the LSE:
This dissertation analyses the problem of how to create more just and democratic global governing institutions, exploring the approach of a more formal system of collective decision-making by the three main actors in global society: governments, civil society and the business sector….
The thesis explains and adopts three philosophical foundations in support of the argument. The first is liberal individualism; the thesis argues that there are strong motivations for free individuals to seek fair terms of cooperation within the necessary constraints of being members of a global society. Drawing on the works of David Hume, John Rawls and Ned McClennen, it elaborates significant self-interested and moral motives that prompt individuals to seek cooperation on fair terms if they expect others to do so. Secondly, it supports a theory of global justice, rejecting the limits of Rawls’s view of international justice based on what he calls ‘peoples’ rather than persons. Thirdly, the thesis adopts and applies David Held’s eight cosmopolitan principles to support the concept and specific structures of ‘Collective Management’.
The author? Saif "we will fight to the last minute, until the last bullet" Gaddafi (son of Muammar).
More background and discussion with David Held, one of his dissertation advisers, here.
Hat tip to Boing Boing.
Sexual Harassment Pay
Economist Joni Hersch applies the theory of compensating differentials to sexual harassment:
Workplace sexual harassment is illegal, but many workers report that they have been sexually harassed. Exposure to the risk of sexual harassment may decrease productivity, which would reduce wages. Alternatively, workers may receive a compensating differential for exposure to sexual harassment, which would increase wages. Data on claims of sexual harassment filed with the Equal Employment Opportunity Commission are used to calculate the first measures of sexual harassment risks by industry, age group, and sex. Female workers face far higher sexual harassment risks. On balance, workers receive a compensating wage differential for exposure to the risk of sexual harassment.
And how much do you get for the risk of a grope? About 25 cents an hour for women and 50 cents an hour for men.
The theory is surely correct although I am not convinced by the evidence which mostly comes from weak data on wages and the differential rate of sexual harassment by industry. I would be more convinced if women's wages fell more in industries with a lot of sexual harassment after increases in prosecution.
Hat tip: Art Carden.
Not From the Onion: The CIA, the NYTimes and Playboy
In Hiding Details of Dubious Deal, U.S. Invokes National Security the NYTimes today reports on how easily the US government was conned out of millions of dollars for software that could supposedly decode secret al-Qaeda messages being transmitted via bar codes in Al-Jazeera broadcasts. You may recall the terror alert of Christmas 2003 when President Bush ordered dozens of trans-atlantic flights to be cancelled and we were told:
A surge in recent terrorism intelligence points to the possibility of a spectacular attack that terrorists abroad "believe will rival or exceed the scope and impact of those we experienced on Sept. 11,'' said Scott McClellan, the White House press secretary.
Apparently the December scare was based on a hoax and not even an elaborate hoax. The con man, a heavy gambler with no serious background in computer science, never gave anyone in the CIA, the Air Force, or Special Operations Command his software or explained his algorithms and no one else ever found any secret messages in Al-Jazeera broadcasts. Moreover, despite the fact that this information went right to the top, few people stopped to ask the obvious questions such as why the hell would al-Qaeda do something ridiculous like embed messages in Al-Jazeera broadcasts? Wouldn't, you know, say an email or obscure web page work better?
On a lighter note this sentence in the NYTimes piece caught my eye:
Hints of fraud by Mr. Montgomery, previously raised by Bloomberg Markets and Playboy, provide a cautionary tale about the pitfalls of government contracting.
Playboy?!!! Determined to investigate further, I discovered that the NYTimes is being somewhat duplicitous since Playboy broke the story and provided a lot more than hints. The Playboy story is in fact quite a bit more detailed than the NYTimes gloss (need I warn you, however, that the adverts make it NSFW?).
Are you surprised that Playboy would break such an important story? I was, that is, until I remembered that Playboy has been uncovering fakes for a long time.
Sticky Budgets
It's not just prices and wages that are sticky, budgets are too. The Council on Foreign Relations points out that U.S. nominal defense budgets hardly ever fall. To get falling budgets as a percent of GDP (let alone falling real budgets) it helps to have inflation or real growth.
All hail (with a little public choice added in), Akerlof, Dickens and Perry.
The Failure of Keynesian Politics
Let's accept for the sake of argument the truth of Keynesian economics. It is now clear that Keynesian politics has failed. But don't take my word for it. Here's Paul Krugman on the great abdication:
…without saying so explicitly, the Obama administration has accepted the Republican claim that stimulus failed, and should never be tried again.
What’s extraordinary about all this is that stimulus can’t have failed, because it never happened. Once you take state and local cutbacks into account, there was no surge of government spending.
If that sounds familiar let's remember that by their own admission Keynesians believe that Keynesian politics also failed during the Great Depression. Again, Paul Krugman on the New Deal:
…you might say that the incomplete recovery shows that “pump-priming”, Keynesian fiscal policy doesn’t work. Except that the New Deal didn’t pursue Keynesian policies. (emphasis in original).
So we have had two major cases that massively favored Keynesian economics but Keynesian politics failed both times. Not that this should be surprising, Keynes himself told us that his theory was more suitable to totalitarian regimes:
The theory of aggregated production, which is the point of the following book, nevertheless can be much easier adapted to the conditions of a totalitarian state [eines totalen Staates] than the theory of production and distribution of a given production put forth under conditions of free competition and a large degree of laissez-faire.
More recently, other people (including Paul Krugman as I recall although I can't find a good link) have said similar things about the chaos of democracy versus the Chinese government's ability to stimulate at will.
Now I will take a large degree of laissez-faire and the chaos of democracy over authoritarian political and economic regimes any day. I assume most Keynesians would as well. Thus, if we can't count on massive increases in government spending during a recession to mop up problems ex-post shouldn't we all, Keynesians and otherwise, be spending more time thinking about ex-ante alternatives to Keynesian politics?
What are the alternatives to Keynesian politics? Greater regulation to prevent crises from occurring is a legitimate response, although one that I wouldn't necessarily buy into in all particulars. Along the same lines, increasing wage, price and real flexibilities (e.g. relocation flexibility and public and private savings flexibility) would benefit us in future recessions. Automatic stabilizers such as unemployment insurance are one area that has worked quite well. What other areas can be automatized? Funding for states? How about an automatic payroll tax cut tied to the unemployment rate? (fyi, Keynes favored the latter).
More generally, we can probably get more agreement today on policies that will operate tomorrow than we can get agreement today on today's policies or agreement tomorrow on tomorrow's policies.
Addendum: Ezra Klein comments and here is Megan McArdle and here is Paul Krugman.
The Pharaoh and the Commanding Heights
The Egyptian military is, for now, looking like a force for democratization. It should not be forgotten, however, that the military is an oligarchy which controls huge swaths of the Egyptian economy.
SFChronicle: It owns companies that sell everything from fire extinguishers and medical equipment to laptops, televisions, sewing machines, refrigerators, pots and pans, butane gas bottles, bottled water and olive oil.
Its holdings include vast tracts of land, including the Sharm el-Sheikh resort, where ex-President Hosni Mubarak now resides in one of his seaside palaces. Bread from its bakeries has helped head off food riots.
Another source of the military's untold wealth is its hold on one of this densely populated country's most precious commodities: public land, which is increasingly being converted into gated communities and resorts. The military has other advantages: it does not pay taxes and does not have to deal with the bureaucratic red tape that strangles the private sector.
…The revenue streams from its various holdings help the military maintain the lifestyle its officers have grown accustomed to, including an extensive network of luxurious social clubs as well as comfortable retirements – all of which helps ensure officer loyalty.
Not surprisingly, the military has opposed privatization and economic liberalization. The Egyptian military currently commands a great deal of respect in Egypt but what happens when a nascent democracy tries to reform an entrenched oligarchy?
World of Snow and Ice
Daily Mail: At first glance it looks like a graphic from a Discovery Channel programme about a distant ice age. But this astonishing picture shows the world as it is today – with half the Northern Hemisphere covered with snow and ice.
The image was released by the National Oceanic And Atmospheric Association (NOAA) on the day half of North America was in the grip of a severe winter storm.
Addendum: It's a cool picture, that is all.
Malaria and IQ
The figure below, from Bill Gates's annual letter, shows that countries with a higher disease burden have lower average IQs. The theory is that building brains and fighting disease are metabolically costly so more effort to fend disease diverts resources from brain development lowering IQ.
Tyler blogged this research earlier writing "I'm not sure the authors have a very good test against alternative hypotheses, but still a correlation remains after making some appropriate adjustments."
Further evidence on causality is given by Atheendar Venkataramani in Early Life Exposure to Malaria and Cognition and Skills in Adulthood. Venkataramani finds that men born after widespread malaria eradication began in Mexico in the late 1950s have higher IQs (Raven scores) and are more likely to work in white collar jobs than men born shortly before eradication efforts began. Importantly, the effect is larger for men born in those states that began with high exposure to malaria.