January 28, 2010
Fear, Profiling, and Terrorism on Airplanes
Fear, Profiling, and Terrorism on Airplanes-Becker
The purpose of terrorism, wherever it occurs, is to create fear that is disproportionate to the size of any terrorist risk. As Posner indicates, many people have considerable fear of flying even under the best of circumstances. This fear is increased when there is an attempt by a suicide bomber to blow up a plane, as happened in December on a Northwest flight going from Amsterdam to Detroit. The fear is multiplied several fold when attacks are successful. Air travel within the US, and between other countries and the US, took a nosedive after the 9/11, 2001 successful multiple attacks on planes going to New York and Washington.
Yona Rubenstein of Brown University and I have studied in detail reactions to the terrorist attacks on Israeli buses and restaurants during the Intifada period. We show that bus travel in Israel fell significantly after every suicide attack on a bus, while the use of taxes and private cars increased. Similarly, eating in restaurants fell rather sharply after a suicide attack at a restaurant, and this was partially replaced by take out orders. To attract business, restaurants began hiring private guards stationed in front of restaurants, and these guards thwarted several attempted suicide bombings.
Airlines have to give a similar reassurance to air travelers by providing a level of security that allays many of their often magnified fears. The optimal level of security on air travel is much higher than would be the case if an exaggerated fear of air travel due to possible terrorism were not so prevalent. For this reason, checking of shoes, laptops, liquids, and even body scanners may be often useful, even when they are not so effective.
In addition, greater profiling of passengers would be desirable. After the December bombing attempt, President Obama did order a more careful check of individuals coming from higher risk countries, such as Yemen. That is a step in the right direction, but it is not enough. Young males of Moslem background have committed virtually all the terrorist attacks against airplanes traveling to, or within, the US. They should have the most invasive security checks. Since it is not always apparent who is a Moslem, this profiling would often have to be proxied by country of origin, name, and other such identifying features. Many law-abiding young Moslem males would be offended by having to go through an especially intensive security check, so they should be treated with the utmost respect. It might also be publicized that such intensive procedures would make it easier for young Moslem males to get American visas.
Terrorist organizations would react to such profiling of Moslem males by trying to find substitutes. Perhaps the closest substitutes are religious young Moslem females, and young non-Moslem males who are sympathetic to the terrorist cause. Therefore, these groups should face tougher security checks than other passengers, but not as tough as young Moslem males. Probably the optimal approach would be to inspect a fraction of members of these groups as carefully as young Moslem males, while the other members would be given a less complete check. Other passengers, such as old women and men, and young children, do not need to receive onerous checks. Since the vast majority of passengers fall into low risk categories, extensive profiling of the high security risks would reduce the overall security effort while at the same time increasing the protection of air travelers from terrorist attacks.
I recognize that explicit profiling is unpopular in some quarters, in part because the profiling of African Americans with regard to crime detection and prevention was abused. Nevertheless, making judgments about the likelihood of different tendencies in various groups is an inevitable part of personal as well as business decision-making. For example, advertisers know that men are more likely to watch sporting events than women, and film producers know that women are more likely to watch love stories, and men are more attracted to pornographic films.
Vigilance is needed to make sure that profiling of passengers is not abused, and that it is conducted politely. Yet it is unwise to give in to political correctness, and require all passengers to go through the inconvenience and loss of time involved in extensive airport security checks, when only a very small fraction of passengers pose a terrorist threat.
Optimal Protection against Terrorist Attacks on Airlines—Posner
In the wake of the attempted Christmas bombing of an American airliner en route to Detroit, there has been a flurry of new security measures. These measures are costly, primarily in delaying the passage of passengers through airport security, but there are also the expenses of additional screening equipment, such as body scanners, and of additional security personnel, such as armed guards on flights and additional screeners in the intelligence agencies.
The economic question is the optimal expenditure on preventing terrorist attacks on airlines. The question is bafflingly difficult because of the uncertainty associated with such attacks. Cost-benefit analysis of precautions is a reliable tool of economic decision making only (in general—I will suggest an exception below) when not only the cost of the precautions and the loss (cost) that will occur if the event sought to be prevented is allowed to happen can be calculated, but also the probability of the event if the precautions are not taken. For that second calculation is also necessary in order to estimate the expected loss if the precautions are not taken. If the loss if the event occurs is $x, and the probability that the event will occur unless precautions are taken to prevent it is.01, then, as a first approximation, one should spend up to $.01* x* to prevent the event from occurring, but not more.
But what is the incremental probability of a successful terrorist attack on an airline if the precautions instituted after the Christmas bombing attempt are withdrawn? Moreover, although that is the most difficult question, there is also uncertainty about the loss should such an attempt succeed. There are pretty good value of life estimates, which would suggest for example that an airline bombing that killed 200 people would inflict a loss of $1.4 billion (200 x $7 million). But that leaves out the terrible fear that these people would experience unless the bombing caused instant death (which it would not), plus the fear of other airline passengers and crew after the bombing, plus added time and safety costs of passengers diverted by fear to other means of transportation—other means that may be more serious, depending on how common successful terrorist attacks on aircraft become; for the death rate per mile is, at present anyway, markedly higher for automobile transportation than for air transportation. There is an instinctual fear of flying (easy to explain in terms of the ancestral environment in which the human brain developed, for in that environment heights were exceptionally dangerous), and as a result the prospect of being killed in an airline crash fills many people with particular dread; that prospect is a cost, like any other. For many people, it exceeds the expected accident cost of driving relative to flying.
But I want to focus on the uncertainty of the occurrence of a terrorist attack. Some statisticians, and some famous economists of yore such as Frank Knight and John Maynard Keynes, distinguish between calculable risk, as in my.01 example, and uncertainty, in the sense of risk that cannot be calculated with any confidence. No one can say with any real confidence what the probability of a successful attack in the next year on a U.S. airline (specifically on a flight originating outside the United States, which seems the likeliest type of terrorist attack) is, except that it is between 0 and 1, which is unhelpful. (It is naïve to base an estimate of probability on frequency, that is, on past occurrences, if there is no reason to believe that the future will be like the past.) In fact not only most travelers but also the airlines and the government think that the probability of a successful airline attack is much closer to 0 than to 1; if they thought it was close to 1, there would be far more radical precautionary measures taken and a sharp decline in demand for air travel.
But it makes a big difference to the optimal investment in precaution whether the probability of such an attack is.0001 or.1 (as it could easily be if the attack was the first in a planned series), and whether the cost of the attack if it is successful would be $1.4 billion or $5 billion--or much more, as it could be, if one thinks that the Iraq and Afghanistan wars, which together have already cost at least $1 trillion, were a consequence of the 9/11 terrorist attacks. There is thus uncertainty in size of loss as well as in probability of loss. As a result of these dual uncertainties, the realistic expected-loss range could, on my assumptions, easily extend from $140,000 to $500 million.
How to pick a point in that range? The question may seem unanswerable, but it is not. The reason is discontinuity in the range of available precautions. Greater vigilance and more screening equipment and screeners are costly but there are sharply declining marginal returns. One might decide to place two or three guards on every international flight, but it wouldn't make any sense to place 10 guards on every flight; the incremental benefit would be negligible. Similarly, maybe every security line in every international airport should be equipped with a body scanner, but it wouldn't make sense to equip every security line with two body scanners. The inability of our intelligence agencies to pool information effectively will be costly to correct, but these are costs that have to be incurred anyway—to protect the nation from a range of terrorist and other threats, not just threats to airline safety.
There is probably a bias among security personnel in favor of doing more than can be justified by the kind of analysis that I have just offered: that is, a bias in favor of adopting some precautions that have little or even no efficacy in preventing attacks, such as subjecting children who have already been patted down in the security line to a second pat-down at the airline gate. The reason for the bias is bureaucratic, or in other words careerist: from the career perspective of a security officer, the worst thing that can happen is an exact repetition of a successful attack. For then no excuses, even if reasonable, for having failed to prevent the new attack will be accepted. So security agencies will tend to overinvest in preventing the repetition of previous attacks. It has been argued persuasively that the nation has overinvested in airline security since 9/11 relative to security against other attacks, for example on trains or subways, because we have thus far been spared such attacks, though other nations, notably Britain and Spain, have not been.