Category: Science

The Addict

The author is Michael Stein and this is possibly the most interesting and engaging book I have read this year.  The subtitle is “One Patient, One Doctor, One Year.”  The ongoing dialogue between a doctor and his addicted patient defies excerpt but here is one small (non-dialogic) bit:

There is violence inside hospitals, and I am often surprised there isn’t more.  In my experience it breaks out most often in the emergency room, the airport terminal of the hospital, the site of comings and goings, of transience, the stopover for travelers, the first landing for the already hurt.  There is pain and fear, there is the anger and frustration that comes with bad luck’s arrival, compounded by the delays — for blood work and X-ray results — where it is clear that the staff is taking care of many people, where you aren’t the only one, just the one they are slowest to assist.

This book covers the notion of rational addiction, how and why people kick addiction, whether addicts are different in the first place, self-deception, the motivations of doctors, what doctors really do, how platonic yet romantic bonds develop, and many related issues.  It is a memoir rather than formal science and it reads as well as masterful fiction, while being thought-provoking on many levels.  Here is one very good review.

The bottom line: I just bought his other non-fiction book.

Your ears make identifiable noise

I was intrigued to read this:

You are the victim of identity theft and the fraudster calls your bank to transfer money into their own account. But instead of asking them for your personal details, the bank assistant simply presses a button that causes the phone to produce a brief series of clicks in the fraudster's ear. A message immediately alerts the bank that the person is not who they are claiming to be, and the call is ended.

Such a safeguard could one day be commonplace, if a new biometric technique designed to identify the person on the other end of a phone line proves successful. The concept relies on the fact that the ear not only senses sound but also makes noises of its own, albeit at a level only detectable by supersensitive microphones.

If those noises prove unique to each individual, it could boost the security of call-centre and telephone-banking transactions and reduce the need for people to remember numerous identification codes. Stolen cellphones could also be rendered useless by programming them to disable themselves if they detect that the user of the phone is not the legitimate owner.

Why do people like streetcars so much?

Will, a loyal MR reader, asks:

I just ran across an interesting post by a Jess Weiss on a
pro-streetcars-for-DC blog that asks the following question – "In
several places in the U.S., most notably Portland, Oregon that's built
the most extensive streetcar system in the U.S. to date, they report
"people simply like streetcars more than buses", but nobody seems to be
able to really point their finger at hard data why that is.

Why do you think streetcars are better than buses?"

Here in Lisbon the streetcars are full of pick-pockets, overcrowded, and hard to keep your balance in.  Yet those same streetcars are beloved by the tourists and common on the postage stamps.

I believe this is a question for Mrs. Cowen, not me.  I did ride them in Lisbon — once.  I'm still wondering why so many people are reluctant to take cabs for cheap, short rides.

Here is a Megan McArdle post on streetcars.  Natasha believes that street car lovers wish to "affiliate themselves with the past."  (When I heard this phrasing I realized we are no longer newlyweds.)  I believe that streetcars help you avoid that "low class feeling" which all too often comes from riding on the bus.  The whole point of a streetcar is to avoid creating an ambience separate from the urban trappings which surround you.  Which is precisely why they are charming yet not always so comfortable.

Here is a short article on the popularity of streetcars.  Putting aside the social cost-benefit analysis, and focusing only on the individual ridership decision, why do people like streetcars so much?

Respecting the elephant

I would not go so far as some who would insist that a Hindu is not the person to ask about Hinduism, as Harvard professor Roman Jakobson notoriously objected to Nabokov's bid for chairmanship of the Russian literature department: "I do respect very much the elephant, but would you give him the chair of zoology?"

That is from Wendy Doniger's new and noteworthy The Hindus: An Alternative History.  Here is a favorable Michael Dirda review of the book.  Read the Wikipedia section on "Criticism" of Wendy Doniger, some of it from fundamentalist Hindus.  Here is a defense of Doniger.

Testosterone and economic behavior: some new results

The story starts off with this:

Women given testosterone for a month were no more likely than women not receiving the hormone to engage in risky financial decisions, according to researchers in Sweden. The findings could suggest that women are a safer pair of hands on the stock-market trading floor than men – or throw into doubt earlier findings about the effect of the hormone on men.

A spate of recent studies have found correlations between testosterone levels and risky behaviour in men, including one that found that male securities traders with more testosterone in their saliva made riskier financial decisions.

But now a team led by Magnus Johannesson, an economist at the Stockholm School of Economics, has found no such effects in a group of 200 post-menopausal women. The women were administered testosterone, oestrogen or a placebo for four weeks and asked to play a series of economic games that measure the player's propensity to take risks, their trust and their willingness to share resources.

One researcher notes:

"I'm relatively pessimistic of finding an effect in men," Johannesson says. He writes in the paper that it is possible that previously published links between testosterone and risk-taking are "spurious". Studies that do not find a correlation between sex hormone levels and economic behaviour may simply have a harder time getting published. "Negative correlation results don't get published," he says.

The original research is here.  I would simply urge caution in interpreting results from this area.  We're not yet in a "safe zone" of knowing what replicable results look like.

What groups talk about

Groups talk about what they already know:

A new meta-analysis (pdf) of 72 studies, involving 4,795 groups and over 17,000 individuals has shown that groups tend to spend most of their time discussing the information shared by members,
which is therefore redundant, rather than discussing information known
only to one or a minority of members. This is important because those
groups that do share unique information tend to make better decisions.

Another important factor is how much group members talk to each other. Ironically, Jessica Mesmer-Magnus and Leslie DeChurch found that groups that talked more tended to share less unique information.

Hey, Alex, demand curves slope downwards!  Hey Robin, people signal!  Hey, Bryan, etc.

The Dark Side?

Gretchen Rubin interviews Todd Kashdan (of GMU I might add, though I don't know him):

Is there anything you find yourself doing repeatedly that gets in the way of your happiness?
There is a dark side to my desire to become an expert in psychology,
knowledgeable about science and literature, skilled as a parent,
mountain biker, and weightlifter, and attentive as a husband. When I
think I know something, I stop paying attention. It happens far too
often and when it does, opportunities close. I constantly have to
remind myself to let go of my ego, let go of my expectations, and stay
flexible and profoundly aware of what is right in front of my senses.

Here is Todd's new blog.  Here is Todd on the Mayan afterlife.  Here is Gretchen's version of phony advertising markets in everything.

Here is Todd's home page, with Todd's lists.

A modicum of sanity on choice

I have not had time to read the original study but this rings true to me:

But now Benjamin Scheibehenne and colleagues have waded into the topic with the claim that the "too-much-choice effect" has in fact failed to appear in many experiments, and with the real-life observation that shops that offer more consumer choice tend to be more successful.

In a series of experiments, Scheibehenne's team tested 598 participants who were asked to choose from among restaurants, charities and music downloads. Throughout, they varied factors that they hoped might explain why the too-much-choice effect sometimes occurs and sometimes doesn't.

Examples of these factors included the need to justify one's choice; the perceived variety of choice, as opposed to actual amount of choice; the mean attractiveness of a range of choices; cultural differences (they tested German and US students); and individual differences such as people's tendency to maximise – that is, their consistent desire to find the perfect option.

For most of the experiments, the too-much-choice effect wasn't actually observed and when it did, the only relevant factor which increased the effect was the need to justify one's choice.

"The fact that most of the variables that we tested were not sufficient to elicit choice overload suggests that the too-much-choice effect is less robust than previously thought," the researchers said.

Repeat this fragment after me: "…the real-life observation that shops that offer more consumer choice tend to be more successful."  

Why do I choose that you should repeat that fragment and not some other?  I'm not going to tell you.

The Case Against Breast Feeding

Hanna Rosin's article on breastfeeding in the latest Atlantic is excellent and would make a topical and accessible introduction to causality studies in an econometrics or statistics class. (And lest that sound damning it's also a great read.)

The general point will be familiar to the audience at Marginal Revolution. The studies that show breastfeeding leads to lower weight, fewer ear infections, less allergies, less stomach illnesses and so forth are almost all observational studies.

An ideal study would randomly divide a group of mothers, tell one half to breast-feed and the other not to, and then measure the outcomes. But researchers cannot ethically tell mothers what to feed their babies. Instead they have to settle for “observational” studies. These simply look for differences in two populations, one breast-fed and one not. The problem is, breast-fed infants are typically brought up in very different families from those raised on the bottle. In the U.S., breast-feeding is on the rise–69 percent of mothers initiate the practice at the hospital, and 17 percent nurse exclusively for at least six months. But the numbers are much higher among women who are white, older, and educated; a woman who attended college, for instance, is roughly twice as likely to nurse for six months.

Moreover, the better we control for other factors that might account for differences in child outcomes between mothers who breastfeed and those who do not, the less evidence there is for breastfeeding's benefits.  Even looking at children within the same family (still far from the gold standard of randomization), shows many fewer benefits from breastfeeding than studies that look across families.  Some modest evidence suggests a gain in IQ and better evidence suggests minor improvements in avoiding some diarrhea.  Rosin does not discount these benefits (so the title of her piece is unnecessarily sensationalistic) but she very appropriately does point to opportunity cost.   

The debate about breast-feeding takes place without any reference to its actual context in women’s lives. Breast-feeding exclusively is not like taking a prenatal vitamin. It is a serious time commitment that pretty much guarantees that you will not work in any meaningful way. Let’s say a baby feeds seven times a day and then a couple more times at night. That’s nine times for about a half hour each, which adds up to more than half of a working day, every day, for at least six months. This is why, when people say that breast-feeding is “free,” I want to hit them with a two-by-four. It’s only free if a woman’s time is worth nothing.

One final point, Rosin's article is also usefully read as a study in propaganda and social psychology.

The Genial Gene

That's the new book by Joan Roughgarden and the subtitle is Deconstructing Darwinian Selfishness.  I'm not sure how true this book is, but if you're looking for a new popular book on evolutionary biology which is engaging, this is the first one in some time.

The book rejects the "Red Queen" hypothesis for why there is sex (e.g., outracing parasites by frequently rolling the genetic dice) and presents a "portfolio diversification" view:

The explanation for why asexual species keep popping up and quickly dying compared with sexual species would seem to be completely explained by thinking of asexual species as genetic versions of get-rich-schemes and of sexual populations as genetic versions of long-term mutual funds, without any need to invoke cost-of-meiosis considerations.

In other words, sex brings a genetic diversity which protects against rapidly changing environmental conditions and thus favors parental genes.

The author also argues against signaling theories of the peacock's tail and against sexual selection more generally (especially on that latter topic I was not convinced but the discussion of sexual dimorphism and why it doesn't always hold is nonetheless interesting).  She presents "social selection" as an alternative and if you turn to pp.237-8 you will see an excellent page-and-a-half summary of what the book is about.  Male promiscuity, for instance, is viewed as a genetic "tactic of last resort."

Recommended, but with caution.  It is a must for anyone who reads about evolutionary biology and by the end of the book I was less skeptical than when I started it.

Here is a summary of Roughgarden's previous book.

Oh Ye of little faith

Mark Davenport reports to me (the link I added):

I noticed your recent blog entry about Rejecta Mathematica.  A couple of us on the editorial staff are semi-regular readers of your blog, so we were happy and excited to see your posting.  I wanted to let you know that we are actually in the later stages of releasing our first issue – just finalizing a few things with the small crop of brave authors who have responded to our invitations.  If you would like, I will let you know when our inaugural issue is available.

Only in England, part II

Spud was found wandering in a garden and taken to Tiggywinkles Wildlife
Hospital in Aylesbury, Bucks, last August. Experts are baffled by his
condition, which has caused his skin to dry and his spines to fall out.
The hospital is asking practitioners of alternative medicine to suggest
possible remedies.

Here is a picture of Spud, a hedgehog with no spines.

I thank Chug for the pointer.

Patents versus Markets

Long ago Jack Hirshleifer pointed out that markets can reward innovative activity even in the absence of patents (H.'s point was actually that markets could over-reward such activity but the point was clear).  If an inventor discovers a new source of energy that requires the use of palladium, for example, he can buy palladium futures, announce his discovery and wait for the price of palladium to increase.  Of course, this only works if the discovery is credible so betting (contra Tyler) is an important way to test the credibility of a theory (e.g. here and here and of course Hanson's key paper Could Gambling Save Science).

All this is by way of introduction to a new paper in Science, Promoting Intellectual Discovery: Patents Versus Markets (press release here).  Bossaerts et al. compare a patent system with a market reward system in an interesting experimental setting.  The innovation is the solution to a combinatorial problem called the knapsack problem.  In the knapsack problem there are Z items each with a certain value.  You must choose which items to put into the knapsack in order to maximize it's value but each item also has a weight and you cannot go over a fixed weight which is set such that you can't carry all the items.  The solution to a knapsack problem is not obvious since it's not always best to include the most valuable items.  The authors argue that solving the knapsack problem is like combining ideas to create a new innovation.  The authors, of course, know the optimal solution to each knapsack problem.

Rewards for creating the innovation are offered in two ways, in the patent method the first person to produce the optimal solution gets the entire reward.  In the market system each participant is initially given an equal number of shares in each item.  The item-shares trade on a market. After the markets close a $1 dividend is paid to each item-share if the item is in the optimal solution, other shares expire worthless.  Thus, the price of the item-shares can be thought of as the probability that the item is in the optimal solution.  (i.e. is palladium in the optimal solution to the energy problem?  If so, it will have a high price.)  Dividends are set such that the total reward is about the same in the two treatments.  Proposed solutions were also collected in the market setting although the solutions per se were not the basis of any reward.

Important findings are that the problem was solved just as often in the market setting as in the patent setting.  Indeed, in the market setting more people solved the problem on average.  There are two possible explanations.  First, the winner-take-all nature of the patent system may have deterred some of the weaker participants from exerting effort.  Second, and more interesting, is that the prices in the market system did in fact incorporate information about the optimal solution – thus market prices may have given people hints about the optimal solution, much like seeing a partial solution to a jigsaw puzzle.

Problems are that the market system can work only if there are rents to be had from market prices.  A new computer chip design, for example, won't change the price of silicon (although even here side-bets may be possible, the inventor knows the manufacturer to whom he sells the invention for example).  Also, the price of an input, like palladium, can be influenced by many things other than the innovation so the market system will typically often involve more risk.  Still this is an interesting experimental approach to a deep problem.

Thanks to Monique van Hoek for the pointer.

Why aren’t non-parametric statistics more popular in economics?

Abel, a loyal MR reader from Valencia, asks:

I've recently been reading an introductory book on nonparametric models (Nonparametric and Semiparametric Models: an Introduction – Härdle et al) and the apparent flexibility of the approach makes me wonder why aren't those models more used in empirical economics.

¿Are their drawbacks too big? (The so-called "curse of dimension")
¿Perhaps it's just economist's community lack of knowledge or willingness to learn?
¿Are they perceived as a threat to conventional or more established estimation methods?

I would be really glad to hear your opinion and also the feedback in the comments.

He could have added "signalling" to the list, since many non-parametric methods are relatively easy and thus do not demonstrate the skill of the researcher.  But the fundamental reason I think has to do with the nature of economics: non-parametric methods are most likely when you don't have a well-defined, formal structural model in mind.  But many MR readers know more about this than I do, so please offer us your opinions…

A new theory of suicide

This morning I read this:

In essence, Joiner proposed that people who kill themselves must
meet two sets of conditions on top of feeling depressed and hopeless.
First, they must have a serious desire to die…Second, and most important, people who succeed in killing themselves must be capable of doing the deed.

Maybe it’s the fault of the press coverage (remember when Modigliani won the Nobel Prize?…”people save for their old age”) but then I thought of this.