Risk, Overreaction, and Control

11-M_El_How many people died because of the September 11 attacks? The answer depends on what you are trying to measure. The official estimate is around 3,000 deaths as a direct result of hijacked aircraft and at the World Trade Center, Pentagon, and in Pennsylvania. Those attacks were tragic, but the effect was compounded by overreaction to terrorism. Specifically, enough Americans substituted driving for flying in the remaining months of 2001 to cause 350 additional deaths from accidents.

David Myers was the first to raise this possibility in a December, 2001, essay. In 2004, Gerd Gigerenzer collected data and estimated the 350 deaths figure, resulting from what he called “dread risk”:

People tend to fear dread risks, that is, low-probability, high-consequence events, such as the terrorist attack on September 11, 2001. If Americans avoided the dread risk of flying after the attack and instead drove some of the unflown miles, one would expect an increase in traffic fatalities. This hypothesis was tested by analyzing data from the U.S. Department of Transportation for the 3 months following September 11. The analysis suggests that the number of Americans who lost their lives on the road by avoiding the risk of flying was higher than the total number of passengers killed on the four fatal flights. I conclude that informing the public about psychological research concerning dread risks could possibly save lives.

Does the same effect carry over to other countries and attacks? Alejandro López-Rousseau looked at how Spaniards responded to the March 11, 2004, train bombings in Madrid. He found that activity across all forms of transportation decreased–travelers did not substitute driving for riding the train.

What could explain these differences? One could be that Americans are less willing to forego travel than Spaniards. Perhaps more travel is for business reasons and cannot be delayed. Another possibility is that Spanish citizens are more accustomed to terrorist attacks and understand that substituting driving is more risky than continuing to take the train. There are many other differences that we have not considered here–the magnitude of the two attacks, feelings of being “in control” while driving, varying cultural attitudes.

This post is simply meant to make three points. First, reactions to terrorism can cause additional deaths if relative risks are not taken into account. Cultures also respond to terrorism in different ways, perhaps depending on their previous exposure to violent extremism. Finally, the task of explaining differences is far more difficult than establishing patterns of facts.

(For more on the final point check out Explaining Social Behavior: More Nuts and Bolts for the Social Sciences, which motivated this post.)

The Politics of Chain Stores: Where to Go for Coffee When Traveling?

25.-coffee-brandsThere are numerous political decisions related to your coffee buying decisions. Heuristics range from the pragmatic (where is closest? what’s cheapest?) to the philosophical (is it free trade/fair trade?). Those are subjects for later posts, though. Over the next week many Americans will be traveling for the holiday season. Whether on the road, in the airport, or in another town visiting relatives, your favorite source of caffeine may not be available.

In these circumstances you are likely to turn to familiar well-known brands like Starbucks. Like the comfort of an embassy in a foreign country, it is a sign of familiarity and predictability. Our discussion has so far been largely hypothetical, but it turns out there is some hard evidence for these patterns:

The researchers [Shigehiro Oishi, Felicity Miao, Minkyung Koo, Jason Kisling, and Kate Ratliff] obtained the number of outlets of a variety of chain stores (ranging from Home Depot to Kay Jewelers) from annual reports filed by the companies. Data on how often people move around was obtained from the 2000 census. Using the statistical technique of multiple regression, the researchers looked at the combined influence of residential mobility (how much people move around), median income, and population of each state as predictors of the number of outlets for these chains. They found that the amount of mobility really did predict the number of outlets of chains in a given state. Population also affected this number (not surprisingly). Median income of families was not a predictor of the number of outlets of chain stores.

You can find the paper here. An post at Psychology Today has references to further studies on the topic.

Does State Spending on Mental Health Lower Suicide Rates?


That’s the title of a new paper (gated) in the Journal of Socio-Economics by Justin Ross, Pavel Yakovlev, and Fatima Carson. Here’s the abstract:

Using recently released data on public mental health expenditures by U.S. states from 1997 to 2005, this study is the first to examine the effect of state mental health spending on suicide rates. We find the effect of per capita public mental health expenditures on the suicide rate to be qualitatively small and lacking statistical significance. This finding holds across different estimation techniques, gender, and age groups. The estimates suggest that policies aimed at income growth, divorce prevention or support, and assistance to low income individuals could be more effective at suicide prevention than state mental health expenditures.

Their paper asks an interesting question, and apparently they are among the first to attempt an answer using empirical data. Suicide is one of the oldest topics of interest for social scientists, going back to Émile Durkheim‘s 1897 publication.

The main problem with the paper’s analysis is the use of observational data to make a causal claim.* As the authors themselves point out, state mental health spending is remarkably stable to the point that if a year of data were missing it could be interpolated by averaging the years before and after. There’s really no exogenous change observed in the sample period–no instance of a state dramatically increasing or reducing its spending is mentioned–so the comparisons are mostly between rather than within states. This setup fails to provide evidence for the authors’ claims such as, “a one percent increase in public mental health expenditures per capita would reduce the incidence of suicide among that group by 0.91 per 100,000 women in this age group [25-64].”

Fig. 1: Ross, Yakovlev, and Carson (2012)

Given the large between-state differences, a cleaner design might have looked at suicide risk for individuals who moved from one state to another. Of course, this introduces the problem that individuals who commit suicide never move to another state afterward. Furthermore, this individual-level data would like be difficult to collect. However, even a small survey of individuals would be a nice complement to this paper’s focus on aggregate statistics. (The authors are careful to point out that their paper does not assess the effectiveness of mental health treatment on suicide outcomes.)

On the positive side, it is nice to see a null finding published in a journal. Findings that are “qualitatively small lacking statistical significance” are not often seen in print even when they are justified. I only wonder in this case whether the findings will hold up.

Some other posts that I have written on mental health issues can be found here and here.


*Yes, the same could be said of much social science. That doesn’t make it OK, nor does it mean that NSF Political Science should be defunded.

Micro-Institutions Everywhere: Time and Lateness

Readers familiar with Latin America or the Middle East will recognize phrases like “mañana,” “Arab time,” or “island time.” All of these connote a local understanding of time that differs from the to-the-minute accuracy  (well, almost) that the West has grown accustomed to since clocks became commonplace. It turns out that these differences influence the amount of precision expected when asking someone the time, or in measuring lateness. From Psychology Today:

For most Americans, “there are eight time sets in regards to punctuality and length of appointments: on time, five, ten, fifteen, twenty, thirty, forty-five minutes, and one hour early or late.” …

Moroccans in the study were more likely than Americans to mentally partition an hour into 15-minute segments.  This may explain, at least in part, why Moroccans and other Arabs are often less punctual than Americans.  An American who arrives 10 minutes after the appointed time is late by “two units of psychological time.”  A Moroccan who is also running late by two units will arrive 30 minutes (“two quarters of an hour”) after the appointed time.

The expression “psychological time” feels a little fuzzy but the overall idea seems plausible: that lateness depends on how many chunks of an hour your culture breaks time into. It can be very hard for travelers from the West to adjust to a different understanding of time in a foreign culture, which often leads to frustration. I know less about how time differences challenge others when they come here. My Arabic teachers were often late, but that may be due to another stereotype–the absent-minded professor. Do these differences operate at a macro-scale, affecting the amount of time considered reasonable for accomplishing a political goal?

Are Assassins Crazy?

The answer to this probaby depends on the image that pops into your head when you hear the word “assassin,” which in turn probably depends (for American readers) on whether you’re old enough to remember the JFK assassination or the attempt on Ronald Reagan’s life by John Hinckley. It turns out that this question has been asked for over 150 years. One of the earliest answers was called the M’Naghten rule (pronounced–and sometimes spelled–“McNaughton”).

The M’Naghten rule resulted from the attempted assassination of Robert Peel by Daniel M’Naghten. His case was decided by a specific series of criteria, the most important of which was whether or not the individual knew that what he was doing was wrong. This rule was the primary legal doctrine for the insanity defense in the Anglophone world until at least 1953, when it was judged to be obsolete.

I became interested in this history when reading Destiny of the Republic, about the assassination of James Garfield. I won’t go into details about his case, but they are interesting in their own right and the book is highly recommended. Allow me to share the author’s description of the rule’s impact, which reminded contemporaries of an earlier attempt on Queen Victoria’s life by Edward Oxford:

“We have seen the trials of Oxford and MacNaughtan conducted by the ablest lawyers of the day,” Queen Victoria had written in disgust to Peel after the M’Naghten ruling, “and they they allow and advise the Jury to pronounce the verdict of Not Guilty on account of Insanity,–whilst everybody is morally convinced that both malefactors were perfectly conscious and aware of what they did!” Before her eventual death in 1901, at the age of eighty-one, Queen Victoria would survive several more assassination attempts. Her husband, who had lived to witness four of them, was convinced that the would-be assassins had been encouraged by Oxford’s acquittal.

This last part strikes me as interesting because of its irony: supposedly insane individuals were thought to be more likely to attempt assassinations when the likelihood of punishment was reduced.*

What does this mean for contemporary political science? Over the past 35 years, and particularly in the last decade and a half, the question of whether assassins, terrorists, insurgents and the like are rational has been a critical but mostly unproven assumption in empirical research on political violence. If it turns out that assassins are more likely to strike in countries where the M’Naugton rule was in effect, this would suggest (but obviously not prove) that assassins respond to changing costs and benefits of their actions.

Further reading: Experts Disagree on Psychological State of Norwegian Killer (via @intelwire)


* Note: I am not in any way advocating for a lack of legal sympathy for mental conditions. This post is meant to demonstrate the possible rationality of a supposedly irrational act.

Bus Schedules as Micro-Institutions

Train schedule

EJ Marey's French Train Schedule, c. 1880 in Tufte (2001) via Marlena Compton

Like many other universities, Duke has a lack of parking in close proximity to its class buildings, and so it operates a free shuttle service to take students and employees from remote lots to their desired locations. Today I parked my car as the shuttle was pulling up to the lot. The driver did not wait. It would have been easy for me to selfishly have become angry, but I didn’t. Why not? Certainly it is not because I am an unusually patient or moral person. It is because I appreciate institutional constraints.

What was the institutional constraint in this case? The bus schedule: the driver was not refusing to pick me up, he was sticking to his schedule. He went on to pick up other people who were already waiting at their stops, rather than making them wait an extra minute for me. If there was even one person waiting, this balanced out on net. If there was more than one person waiting, everyone benefited from him leaving me behind. Everyone? Even me? Yes, because I knew that he would be back less than 10 minutes later, and so I was able to wait. Everyone’s expectations were clear, and everything worked out fine.

How can we generalize this to other cases? Through the development of a theory about institutions. In general, I would suggest that an institution does the following:

Clarifies priorities. The priorities of a bus schedule are regular and timely service. By making these explicit and clear, both the bus driver and I knew what to expect from our interaction. He did not have to feel guilty about leaving me behind, because he would be back in a few minutes and there were other stops on other routes that I could go to instead. I did not have to get frustrated, because I knew those same two facts.

Delineates roles. The bus schedule makes it clear who is doing what and when. It is not my job to drive the bus, but to be on time. This clear delineation of roles made it clear who or what was responsible for each contingency. If I miss the bus, it is my fault. If I make it onto the bus, it is because I was on time. But if I make the bus late by causing it to wait for me, other passengers will blame the bus driver and not me. The delineation of roles then, helps with accountability and fairness.

Depersonalizes interactions. You may have noticed that I keep using the phrase “bus driver.” Is it rude of me not to know his name? I don’t think so. I encounter at least a dozen different bus drivers a week, so while it might be polite of me to say “please” and “thank you” (as I do), it requires a lot of memory to get to know all of their names. They know this, and do not expect it. No matter which driver it is, though, I expect to get to my destination on schedule and they expect a modicum of politeness. They neither get certain people there faster due to VIP status, nor refuse service to individuals because they are, say, preoccupied Ph.D. students.

One important caveat to the last suggestion is that the same person performing a number of different roles over time can re-personalize them. If the bus driver does only that, I do not get mad at him for sticking to the schedule. But if I encounter him next week as a server at a restaurant, and next year as a student, my attitude toward him will depend more on the quality of my interactions with him than the institutional constraints. That is, I am more likely to get mad at him if he is rude to me every time than to attribute his rudeness to an institutional constraint. This is how Robert Gates went from being a virtually anonymous CIA employee to a very recognizable, political personality by the time he retired.

How general and how valid do my thoughts about institutions seem to you?