A confession to the Reverend Bayes and a modest proposal

In which a blogger sees the Bayesian light.

A footnote (154) in Daniel Kahneman’s great book Thinking, Fast and Slow had me puzzled.

Consider a problem of diagnosis. Your friend has tested positive for a serious disease. The disease is rare : only 1 in 600 of the cases sent for testing actually has the disease. The test is fairly accurate. Its likelihood ratio is 25:1, which means that the probability that the person who has the disease will test positive is 25 times higher than the probability of a false positive. Testing positive is frightening news, but the odds that your friend has the disease …

(Before clicking to the jump for the answer, make your own estimate.) Continue reading “A confession to the Reverend Bayes and a modest proposal”


Are they based on evasions as much as agreements?

Quote of the day, from a good post by Ken Kersch on the ability of American conservatives to paper over their contradictions:

Political alliances are complex amalgams of not only actions, decisions, and convictions, but also of silences, evasions, and symbols.

Is it a permanent disadvantage of the left, which aspires to a politics of reasoned argument and persuasion, that we are bad at silence and evasion?

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Awards and Class

A combination of union rules and asbestos in the walls makes it illegal for me to hang pictures and plaques in my hospital office. That task was undertaken by a friendly fellow who, drill, screws and hooks in hand, informed me that I had ill-chosen the placements of the plaques displaying my degrees.

My undergraduate, master’s and doctoral degrees are important to me — they represent seven years of my life after all — but I feel fulsome displaying them. I therefore had selected for them a strip of bare wall between a bookcase and a rear corner of my office. In this position, I would be able to see them but my office visitors would not.

The picture hanger objected “You ought to be proud of these, doc. Put them out here where everyone can see them!” And though I am proud of them, I did not comply. Why did we see the matter so differently?

The anthropologist Kate Fox documents that this is a subtle difference between social classes. Working class people generally keep their plaques, certificates and sporting trophies in the front room for all to see, and indeed feel comfortable pointing them out.

As we ascend to the middle of the class ladder, we find such honesty unfashionable. Perhaps we want to conceal our vanity and ambition because it’s a wise career move, or perhaps being modest makes it more likely your colleagues will give you awards because they don’t yet find you insufferable.

The dilemma for middle to upper-middle class strivers is that they want everyone to know about their awards without looking as if that is precisely what they crave. Fox is spot on in diagnosing how most British upper-middle sorts handle this: They hang their awards in the lavatory. All houseguests will thus be sure to see them, but the larky placement will suggest that the winner of all these laurels doesn’t think much about them, after all, they hung them in the loo, didn’t they? An American friend has her “nonsense wall” of awards, explicitly referred to as such, which has a similar effect of displaying achievements while at the same time appearing not to value them. Another American approach: Hang them in that dusty spare room where you also happen to put overnight guests whom you wish to impress.

What about the upper class? Self-made American uppers usually follows the working class model: Donald Trump and his ilk can never shut up about all their putative achievements and will mention them without the slightest provocation. However, a sliver of the American upper class and most of the British upper class are extraordinarily reticent about their honours, even when pressed on the point. After all, they can afford it, and they don’t need pieces of paper to assure them of their relative place in life.

The truly classiest approach I have observed, in the sense of the word “class” that Michael O’Hare so well explicated? A senior colleague who was so famous he could not attend a conference without receiving a plaque kept them all in a stack under his desk. He had space on his office wall for exactly one. When he was scheduled to receive a visitor from, say, the Royal Astronomical Society, he would dig through his plaques and hang the matching award in the place of the honour. He would then say to his guest “Normally I don’t make much of awards, but yours was so special to me that it’s the only one I display in my office”.

The charitable deduction: Beyond “Will not!” “Will so!”

Kudos to my nonprofit consulting colleagues Campbell and Co. for sponsoring a study by the Indiana University Center on Philanthropy to determine the impact on giving of increased marginal tax rates and a cap the charitable-giving deduction.  While some of us have been arguing that both of these moves toward social justice should be supported by the nonprofit community, and others have been arguing that the world will come to an end if every penny of tax savings isn’t afforded to the generous rich, these institutions decided to look for the facts.

The facts–as elegantly stated in a Congressional Research Service study that came to the same conclusion–are these:

The estimated effects of the cap and other elements of the budget package depend on whether the proposals are compared with the current tax rates of 33% and 35% or the rates scheduled for 2011, 36% and 39.6%. Compared with current rules, estimated effects are between one-half a percent and 1% decline in charitable giving . . . . When compared with tax rate provisions in 2011, charitable deductions are estimated to fall by about 1.5% if only the cap is considered, but if income effects from the entire budget package are included contributions actually rise 2.5%.  The relatively modest effects of the proposal arise because (1) the effect of caps on the subsidy value is limited, (2) only a fraction (about 16%) of charitable giving is affected, and (3) because evidence suggests that behavioral responses to changes in subsidies are relatively small.

(Emphasis mine.)  To paraphrase: the tax subsidy isn’t much reduced; that small reduction doesn’t affect 84% of charitable giving; and, in fact, charitable giving isn’t all that tied to tax benefit.

So whether we take the IUPUI findings that charitable giving is likely to decline modestly if these tax reforms are enacted, or the CRS findings that it might actually go up, we should realize that everyone who’s hyperventilating about the impact of these changes on their poor struggling private school, museum or hospital should just take a deep breath.   Given that the reforms will support many of the social programs, environmental protections, educational institutions and health care options the nonprofits themselves seek to provide, it’s about time for the community to stop whining and agree to pony up.


Focusing on the Wrong Drug in Mexico and Central America

Like Mark, I attended the Yale Globalization Center conference on drug policy organized by President Ernesto Zedillo and Professor Jody Sindelar. The most interesting thing I learned from the panels and participants is that the attention of the U.S. public regarding drugs is focused on debates that don’t matter much for our friends south of the border (i.e., what should we do about marijuana?). Meanwhile cocaine, which has dropped off the public’s radar, is absolutely central to what is occurring in Mexico and Central America.

Mexican gangs grow marijuana and ship it north, no muss no fuss, but to control the cocaine trade they need to look to South American suppliers and the land trade route through which the drug flows. Recently the gangs have established a substantially greater presence — with attendant violence and corruption — in places such as Guatamala, Nicauragua and El Salvador. Whether U.S. policy on marijuana gets tighter, looser or stays the same makes little difference to these Central American countries, but our policies toward cocaine have huge consequences for them.

More generally, the financial import of marijuana to the Mexican gangs seem to be declining. The gangs are diversifying into a range of other criminal and legitimate businesses, making drugs a smaller part of their revenue stream. The U.S. marijuana market is perhaps one sixth of that shrinking slice of the pie. In contrast, despite the increasing diversification of the gangs into non-drug businesses, cocaine remains massively important to them, likely accounting for more revenue than all the other drugs put together. With cocaine’s almost one hundred fold markup from Bogota to Laredo and its incredible weight to value ratio, even a shrinking U.S. cocaine market is extraordinarily lucrative.

Simon de Montfort, Father of Parliament (not)

Hume debunks the still-received story.

My schoolbook history gave Simon de Montfort, 6th Earl of Leicester, credit for founding Parliament.  English kings had been advised by a council of their principal tenants since before the Conquest, but de Montfort was the first – in 1262 to summon commoners to join the assembly.

Starting from that belief, it’s not hard to find irony in the fact that de Montfort’s father (also named Simon) was one of the military leaders of the crusade against the Albigenses, perhaps the first action in European history that deserves to be called genocide.

If this sort of historical irony displeases you, then you will be pleased, as I was, to find that the received story is not quite right.   According to Hume’s History of England (Chap. XIII) , de Montfort did indeed summon representatives of the boroughs as part of his attempt to usurp the powers of Henry III, but that usurpation and de Montfort’s abuses of power left a bad taste in English mouths, and the idea of adding commoners to the Great Council was rather discredited than legitimized by its association with de Montfort’s scheme.

As Hume tells it, the origin of the Commons was the need of the monarchy for revenue.  Henry’s son Edward I, finding himself in fiscal straits due both to structural changes unfavorable to the monarchy and to his aggressive campaigns in Wales, Scotland, and Poitou, found that his best source of new revenue were the boroughs, towns given a measure of local self-government under royal charter.   While the king had the legal authority to tax the boroughs, he lacked the force to collect such taxes unless the burghers were more or less willing to pay them.  Instead of negotiating the amounts borough-by-borough, he preferred to summon representatives of all the boroughs at once, lay out the sums he needed, and get them to agree as a group to supply his wants:  “As,” he proclaimed, “it is a most equitable rule that what concerns all should be approved of by all, and common dangers be repelled by united efforts.”   [Alas, the extant record does not include the critical press releases no doubt issued by Grover Norquist and the Club for Growth, explaining that Edward’s ideas would inevitably lead straight to Socialism.]

Edward’s innovation did not cause the House of Commons – combining the borough representatives with two knights from each shire – to spring into existence full-grown and fully armed.   Edward’s Parliaments did include the shire knights, in addition to the barons who had traditionally made up the Great Council and the newly-summoned burgesses.  But the burgesses plus the knights did not constitute a separate body from the House of Lords.  The barons and the knights deliberated jointly on matters of national concern, while the burgesses met only to approve their own taxation.  The legislative powers of the commoners accreted slowly, starting from the practice of  presenting petitions (“bills”) for redress of grievances as an implicit exchange for the supply of revenue.

On behalf of David Hume, I am happy to offer comfort to the .01% of you who were distressed about owing your political freedom in some measure to the son of a mass murderer, and to the possibly larger number who prefer structural to “great-man” explanations for important changes.

Highways of metallic isolation

L.A. would be great if not for the billboards. That, and teenagers driving Hummers. Oh, tourists, also.

Los Angeles is blessed with a stupendous natural environment, and a somewhat-less-so built environment. I don’t have a ready solution to the blight of Tuscan-style corner malls, but when I am named Grand Vizier of Westwoodistan my first edict will be to abolish billboards* (I’m sorry—”outdoor advertising”).



Continue reading “Highways of metallic isolation”


The new PM of Pakistan is being sworn in, in English. Sounds odd. Apparently, Urdu is the national language and the language of the Constitution, but English is the official language.

I understand that there’s a lot of resentment against native Urdu speakers and the dread Indian influence, but almost everyone understands Urdu, whereas only about half the population understands English. Considering that most of the oath of office is a swearing of fealty to Islam, perhaps it should be in Arabic.

Staid lions and immortal porpoises

I think “to Spitzer” will soon be a verb.

So, if Elliot Spitzer had just answered an ad in the back of Washington City Paper, instead of arranging for an escort to travel from NYC to DC, he wouldn’t be in trouble right now.

Gov. Eliot Spitzer has been caught on a federal wiretap arranging to meet with a high-priced prostitute at a Washington hotel last month, according to a person briefed on the federal investigation.

The wiretap recording, made during an investigation of a prostitution ring called Emperors Club VIP, captured a man identified as Client 9 on a telephone call confirming plans to have a woman travel from New York to Washington, where he had reserved a room. The person briefed on the case identified Mr. Spitzer as Client 9.

Federal prosecutors rarely charge clients in prostitution cases, which are generally seen as state crimes. But the Mann Act, passed by Congress in 1910 to address prostitution, human trafficking and what was viewed at the time as immorality in general, makes it a crime to transport someone between states for the purpose of prostitution.

Who knew that the Mann Act was still in force? I didn’t, but then again I am neither a former NY State Attorney general/prostitution-ring prosecutor nor a john. Electricians know better than to stick a fork in a toaster.

Update: Slate.com has more than you want or need to know about this affair. Except for this:

Kristen told Rachelle that she collected $4,300 from Client-9 and said, “I don’t think he’s difficult. I mean it’s just kind of like … whatever.” Rachelle answered that she’d heard otherwise. Client-9, she’d been told, “would ask you to do things that, like, you might not think were safe—you know—I mean that … very basic things.”

“Basic things?” On second thought, I don’t need to know.

But $1750/hr? Spitzer can hire the most expensive lawyer in America for less than that.