On Kenneth Waltz

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Ken Waltz, arguably the most influential scholar in International Relations of the past half-century, passed away last night. He was 88. It is tough to find anything to say that does not sound contrived. Instead, I wanted to share a lasting memory of mine from John Mearsheimer’s seminar on realism at the University of Chicago. We were reading Waltz’s Theory of International Politics and after a couple of hours of discussing the basics most  are familiar with (balancing, the benefits of bipolarity, etc.), we had gotten into some of the more obscure parts of Theory (there is a fascinating discussion of the meaning of power towards the end that is always worth a re-read). At the end of the latter discussion, John admitted that even though he had read the book countless times (and written insightful analyses of the work), the day’s seminar had brought out something new from the book for him. Years later, reading Theory for the nth for my comprehensive exam in IR, I finally understood what John meant. It’s amazing how much insight Waltz packed into one work. Every new reading truly produces something new for the reader. And this is true not only of Theory but also of much of his other work, including Man, the State, and War.

I met Waltz for the first and only time at a small conference at Yale last year. Not only was he incredibly nice to me and my fellow graduate students (always appreciated!) but tremendously incisive and sharp during the substantive portions of the conference. It was difficult not to be star-struck. Rest in peace, Professor Waltz: you will be missed by generations of students of international politics.

Terrorism Data Remains a Mess

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I’ve recently been trying to get a handle on terrorism trends in Pakistan, and in that process have been reminded of the problems in terrorism datasets. Based on extant data, I could tell you two stories about Pakistan: terrorism in Pakistan is either getting progressively worse or has gotten considerably better since 2009.

Here is the basic trend for terrorism in Pakistan using the National Consortium for the Study of Terrorism and Responses to Terrorism (START) Global Terrorism Database (GTD).

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Compare that with the trend for all terrorism using the National Counterterrorism Center’s World Incident Tracking System. (Through some process opaque to me, the U.S. government decided to stop producing this data series. Or they likely continue to produce it, but just don’t provide it to the outside world. And ignore the redline, which is just the mean across the years shown.)

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If you believe GTD, you should be really worried about Pakistan. If you believe NCTC, we may have turned a corner. Get your “Mission Accomplished” banner ready.

The evidence is a little more consistent when looking at just suicide terrorism. Here is the data from the University of Chicago’s Project on Security and Terrorism (CPOST). Sadly, this data hasn’t been updated since October 2011, suggesting they ran out of funding, and also meaning the 2011 data below is incomplete. But, the data suggest a strong peak at 2009, and then sizeable decreases since then, even with the incomplete 2011 data.

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Finally, compare that with the GTD data for just suicide attacks. Strong peak in 2007, and then a more modest decline since then.

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I don’t have much in the way of conclusions, but despite how many asterisks are found in coefficient charts, we should be skeptical of terrorism findings that are not robust across datasets, and given the discrepancies across data sets, such robustness may be unlikely. The long twilight struggle for cumulative knowledge continues.

Nuclear Weapons and War

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I wanted to flag a soon-to-be-published article by my colleagues at MIT, Mark Bell and Nicholas Miller, looking at whether and how nuclear weapons possession affects conflict.

The paper is interesting on both substantive and methodological grounds. Substantively, they find no statistically discernable difference in the conflict propensity of states with offsetting nuclear arsenals. This is true even at low levels of conflict. These two findings combined mean they find insufficient evidence to support the existence of a “stability-instability” paradox where the presence of nuclear weapons both deters full-scale war while also increasing the likelihood of lower levels of violence.

I think the methodological point they make is perhaps more important, at least for political science practitioners. There was an established paper in the field that found empirical support for the stability-instability paradox, a paper by Rauchhaus (2009). Rauchhaus made a few mistakes, and helpfully for those of us playing at home, mistakes that we probably could imagine making ourselves.

Empirically, he coded the 1999 Kargil conflict between India and Pakistan as a non-war. The number of casualties in that conflict is somewhat in dispute, and alas for us, it is either immediately below or immediately above the 1,000 battle deaths standard that has come to define “war” in political science. Rauchhaus generally relied on the Correlates of War coding of conflict, except in the Kargil case, which means that Rauchhaus accepted the Correlates of War coding for many wars with fewer casualties than Kargil. The empirical finding that nuclear dyads are less likely to fight wars is entirely dependent on whether or not Kargil is coded as a war. If it is coded as a war, then there is no statistically significant difference between nuclear dyads and their non-nuclear counterparts. Though Bell and Miller do not mention it, Kargil has the potential to play a similar spoiler role in the deterministic-variant of the democratic peace literature, and so people would be well advised to always pay attention to Kargil in their dataset if war is an important IV or DV. Montgomery and Sagan (2009) had flagged this a while ago, but it’s not clear to me it has fully sunk in.

The other error is also one that could be made more generally, and so should be of interest to political scientists uninterested in war or nuclear weapons. He used a canned package in Stata called xtgee, which estimates a logit generalized estimating equation (GEE). Exciting stuff, no? The problem is, that when Kargil is coded as a non-war, then there are no wars between nuclear dyads, which creates “separation” in the data. Nuclear weapons predict non-war perfectly. This should lead to non-identification in GEE, or logit, or probit models. The computer should yell at you in such instances. In this case, the xtgee command in Stata erroneously allowed for a coefficient estimate to be produced, and hence Rauchhaus found what he found. Rauchhaus might have realized his results were fishy if he had produced a table of relative risk tables instead of just reporting coefficient estimates in the article. If he had done so, he would have realized his coefficient suggested non-nuclear dyads were 2.7 million times more likely to go to war than nuclear dyads. Bell and Miller use an estimator developed by Firth that allows for parameter estimation even with separation in the data (a downloadable firthlogit package is available for Stata users).

Separation is a fairly common problem, particularly for small datasets or datasets with rare events in them that are dichotomously coded. It should be underlined that a common response of statistical programs is to drop variables with separation, which permits a computational solution, but probably biases the results on the remaining variables. This webpage by UCLA helpfully walks through how different statistical packages handle the problem. Others who are methodologically smarter than me have convinced me to always fit a linear probability model onto my data as a robustness check. Linear probability models also do not suffer from separation. And if the coefficient estimates are radically off, you should just be prepared to defend your estimator choice very strongly.

Survivorship Bias, Sample Sizes, and the Oregon Medicaid Study

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I think most coverage of the Oregon Medicaid Study [gated] has been bad. Very bad. I wanted to flag one way that it has been especially bad.

We don’t do very much U.S. domestic politics on the Smoke-Filled Room but I think the broader methodological issues are worth highlighting. So, for those that don’t obsessively follow wonkish U.S. policy debates, a bit of background. When Oregon expanded Medicaid coverage a few years back, it did so via a lottery. That allowed researchers to compare outcomes between those who received Medicaid and those that did not. And they found no statistically significant improvement on several metrics of physical well being (cholesterol checks, blood pressure checks, etc.). They did find statistically significant improvements in terms of mental health (principally depression) and financial health (apparently from not having catastrophic health expenditures). In general, physical metrics moved in the expected direction (lower blood pressure) just not sufficiently in that direction to be indistinguishable from zero. This could either be true evidence of a null relationship between insurance and health outcomes, or it could be a sign that the study was too small to capture changes in those outcomes. If you look at the study, the fact that something like 22 out of 25 metrics move in the expected (healthier) direction, even if they don’t move far in that way, suggests to me that Medicaid does improve health outcomes. But that’s a separate issue.

Two conservative, smart writers are Ross Douthat of the New York Times and Megan McArdle of the Atlantic. Both are forced to acknowledge that the Oregon Medicaid Study shows Medicaid coverage generates strong financial and mental health benefits for Medicaid recipients, but argue rhetorically: Wasn’t this about saving lives? Douthat asks, “The health care law was sold, in part, with the promise (made by judicious wonks as well as overreaching politicians) that it would save tens of thousands of American lives each year.” McArdle, drawing on the same rhetorical playbook stresses, “[W]e heard that 150,000 uninsured people had died between 2000 and 2006.” See, classic liberal over-promising and under-delivering. You told us poor people would live, not that they would be less depressed and more financially secure.

The important thing is that the Oregon Medicaid Study was a “post-treatment” survey. I’m using “treatment” in the jargon-y way. I just mean assignment via lottery to either the “treatment condition” of receive Medicaid for two years or the “control condition” of continuing insurance free for two years. It’s right there on the first page of the article: “Approximately 2 years after the lottery, we obtained data from 6387 adults who were randomly selected to be able to apply for Medicaid coverage and 5842 adults who were not selected.” To be even more precise, and requiring Douthat and McArdle to turn to the second page of the article, they collected this data via in-person interviews.

Let’s just stop right here. Dead people tell no tales. Hence they were not included in the study. The study occurred only on those people that lived to talk at the end. Medicaid could have saved 1000 lives in Oregon and this research design would not have noticed. Or Medicaid could have killed 1000 people. Same thing. This is what we like to call survivorship bias. It’s so simple, I don’t see the need to belabor the point.

But let’s imagine the study had been designed differently. At this level of power, would we have noticed? A little quick math: about 20% of Americans are uninsured, studies suggest being uninsured is associated with about 20,000 additional deaths a year nationally (U.S. population ~300m), and the control group was about 6000 people. The expected value of uninsured “excessive” deaths in this study is this rate of “excessive” deaths caused by lack of insurance per uninsured person per year times the total number in the control group. I think that gets us about 2 excessive deaths per year, or 4 excessive deaths for the period under study. I’d be very surprised if this study would be able to discern, in a statistically significant way, if Medicaid saved lives. (The death rate in the United States is 799.5/100000, meaning out of our 6000 folks, we’d expect about 96 deaths in these two years.) Even without survivorship bias.

My point: the Oregon findings in no way impugn the possibility that 20,000 Americans a year die from lack of insurance, and that Medicaid might save them. This is true solely because of survivorship bias, though sample size problems make it doubly true.

Missing Women, Missing Mechanisms

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In 1990, Amartya Sen coined the term ‘missing women’ to denote the shortage of women contributing to the skewed sex ratios in Asia and Africa, where men outnumber women, in stark contrast to North America and Europe, where women outnumber men. Estimates of missing women were originally meant to represent some measure of the degree of gender discrimination. This discrimination was attributed to three main causes causes: sex-selective abortions, female infanticide, and the comparative neglect of female health and nutrition during childhood, which led to their deaths early in life.

In 2010, Anderson and Ray, used the Sen-Coale counterfactual, which compares birth and death ratios of men and women in developing countries to similar populations in developed countries, in order to examine the ratio of these missing women across both age and diseases levels. They found a wide variation in the pattern of these missing women between India and China.

“A large percentage of the missing women in China are located before birth and in infancy. We estimate that around 37–45% of the missing women in China are due to prenatal factors alone. But the numbers for India are more evenly distributed across the different age groups.”

In a more recent work in 2012, they further explore the unlikely distribution of missing women across India, and find that

“… a total of more than two million women in India are missing in a given year….First, the majority of missing women, in India die in adulthood. Our estimates demonstrate that roughly 12% of missing women are found at birth, 25% die in childhood, 18% at the reproductive ages, and 45% die at older ages.”

They also find a great deal of variation in the distribution of missing women by age group across the states: Punjab is the only state where the majority of missing women are found at birth, while Haryana and Rajasthan are the only two states where a majority of these missing women are either never born or die in childhood.

The above results show us that commonly considered explanations such as sex-selective abortion or female infanticide cannot explain the age distribution of these missing women. This is certainly true in India and may hold for other countries with similar distributions of missing women as well. It is not as if the woes of adult women are completely ignored (see Chen and Dreze (1992) and Kochar (1999) ), but contrary to conventional wisdom, it turns out that excess female mortality in adulthood is as serious of a problem as missing girls who are never born or die prematurely in childhood.

So what are some possible mechanisms for the existence of so many ‘missing women’ in adulthood? More importantly, is the number high due to differentiated access to healthcare leading to higher maternal mortality and other diseases or due to overt social basis of gender discrimination leading to dowry death and bride-burning? Bloch and Rao (2002) document how women who pay less dowry are more likely to be victims of marital violence. More research is needed to tease apart these mechanisms and understand the reasons behind the surprisingly large number of ‘missing women’ in adulthood. From a policy perspective, at time when new legislation against sexual violence is being debated in India, it is also important to have a broader conversation about the kinds of discrimination being faced by adult women in order to find the most effective ways to address it.

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Would a U.S.-Led Intervention Drag Out the War in Syria?

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The debate over whether or not to intervene in Syria draws on two logics that portend inaction. First, political scientists claim that external meddling in internal conflicts only leads to protracted wars – interventions lengthen, not reduce, conflicts. Second, to actually arm Syria’s rebels would require armaments such as manpads and other hardware that could be used against Israel were an Islamist government to assume power in a post-Assad Syria, not unlike how the Afghan mujahedeen turned against the United States after the Soviet invasion.

Let’s dissect the above. First, scholars find that interventions, especially those on the side of rebels, do prolong civil wars. But the evidence, drawn mostly from the Correlates of War (COW) dataset, may be heavily skewed because of a few protracted conflicts – namely civil wars in places like Angola that saw no shortage of external involvement – and also suffers from selection issues. For instance, it is possible that outside powers select into civil wars because they are protracted, not that the act of arming one side makes war last longer (Page Fortna points to similar selection issues to explain “successful” outcomes of UN peacekeeping missions). Indeed, it is unclear why tipping the balance of power toward one side would make war last longer. The supply of arms and other supplies is less studied. In at least one case – the French intervention against the British during the American Revolutionary War – the supply of arms after the Battle of Saratoga definitely tipped the balance of power in the Yankees’ favor (of course, it helped that the French sent their navy too). Also, Iraqi insurgents enjoyed very little external support yet were arguably able to fight the United States to a long (ten years and counting) and ugly stalemate (We also know that unarguably the presence of a NATO no-fly-zone drastically reduced what would have been a drawn-out civil war in Libya). In other words, not arming the Syrian rebels does not mean the war will end any sooner, it only means we will have no skin in the game in a post-Assad Syria.

In Never Ending Wars (2005), Ann Hironaka argues that the spate of outside interventions was a function of the spread of weaker states after World War II which were unable to control their borders. Nearly 3 out of 4 civil wars since 1945 have experienced third-party intervention, most of which have entailed the supply of arms, aid, and bases, not putting boots on the ground. Of the 49 conflicts with no third-party intervention, the average length of conflict was 1.5 years. By contrast, those with outside intervention saw an average length of 7 years. However, these conflicts were protracted largely because outsiders were intervening on both sides (external intervention by major powers during the 19th century was more one-sided and thus actually made such crises shorter, not longer).

Indeed, I would argue that the literature on external interventions is not entirely undivided. Nile Metternich, for example, finds that interventions by international organizations (e.g. NATO), especially those with democratization mandates, are associated with shorter conflicts, provided rebel leaders come from ethnic groups representing more than 10 percent of a country’s population (which would fit Syria’s largely Sunni opposition). Clayton Thyne looks at unobserved variables (e.g. high levels of resolve among the combatants) that contribute to the resolution of conflicts even with third-party interventions.

The notion that somehow arming Syria’s opposition means a long and protracted war is misguided and driven by a realist-inspired desire to stay on the sidelines and never intervene anywhere. Several foreign policy experts chalk it up to a political gesture and a way to check the box that we are merely doing something. That is bunk. Arming the opposition would send a clear signal to the Assad regime that the president’s words are not merely rhetoric, that there is a responsibility to protect citizens and refugees, and that we can tip the balance of power in the rebels’ favor. It would also help wean the influence of Islamist actors in the region, since many of the arms flowing into their hands are coming from Qatar and other places that favor Islamist over secular groups.

On the second point, would arming the opposition have blowback effects against allies such as Israel after the war ends? This is obviously a concern but it should not lead to a policy of paralysis. Israel, after all, has responded to attacks from the Assad regime and has even provided military intelligence related to alleged chemical weapons use in Syria. We should no doubt screen which factions within the opposition receive light weaponry, but more importantly, we should be clear that the opposition is not predisposed to turn against the United States or Israel should Assad fall in the near future. That can be done through providing them with assistance – intelligence, training (which we are doing in Jordan), funds, etc. – contingent on future behavior. A stronger opposition will face less chance of a reconstituted Alawite faction trying to wrestle control of a Sunni-led regime (albeit the risk is that we may be arming them to fight the Alawites should Assad fall, a risk worth taking).

Not arming the rebels both scratches our realism itch to not involve ourselves in messy internal wars, as well as not arm a potentially hostile future Syria that would pose a threat to Israeli citizens. The second scenario is real, but the first should be discounted: doing nothing (or at the least, giving the rebels non-lethal equipment and some humanitarian aid) is not an option. The U.S. will get pulled into the conflict, either on our terms and our timeline, or on terms we do not foresee (consider a Syrian strike against Israel, which would draw us in). To be sure, by arming the opposition we will be taking sides in a seriously bloody civil war. But this is not Vietnam or Afghanistan in the making. Arguably Syria matters more than these two states to their respective regions’ balance of power. As Syria goes, so goes the Middle East. A victory by Assad cements the continuing influence of Iran and Hezbollah to stir up trouble in the region, from nuclear proliferation to terrorist attacks. The removal of Assad at least provides an alternative, albeit less predictable, path forward for the region. Yes, Islamists would likely wield more power in a post-Assad Syria but that is not guaranteed to spell deteriorating Israeli-Syrian relations or war. Israel still possesses a powerful nuclear deterrent and the backing of the U.S. The worst possible scenario for Israel is a worsening civil war on its doorstep, not an Islamist in power in Damascus.

The fate of Syria will reshape the Middle East for generations. The Obama administration’s defeatist attitude and deer-in-headlights policy will only prolong the conflict, not hasten its successful conclusion.