nancylebov (nancylebov) wrote,

Assassination Statistics

Assassinations are a persistent feature of the political landscape. Using a new data set of assassination attempts on all world leaders from 1875 to 2004, we exploit inherent randomness in the success or failure of assassination attempts to identify assassination’s effects. We find that, on average, successful assassinations of autocrats produce sustained moves toward democracy. We also find that assassinations affect the intensity of smallscale conflicts. The results document a contemporary source of institutional change, inform theories of conflict, and show that small sources of randomness can have a pronounced effect on history.

I'm not qualified to judge the math, so I'm just giving you a few interesting conclusions and details....

The study is of all the assassinations and serious attempts they could find since 1875: 298 attempts, of which 59 killed a leader.
In particular, transitions to democracy, as measured using the Polity IV dataset (Marshall and Jaggers 2004), are 13 percentage points more likely following the assassination of an autocrat than following a failed attempt on an autocrat. Similarly, using data on leadership transitions from the Archigos dataset (Goemans et al., 2006), we find that the probability that subsequent leadership transitions occur through institutional means is 19 percentage points higher following the assassination of an autocrat than following the failed assassination of an autocrat. The effects on institutions extend over significant periods, with evidence that the impacts are sustained at least 10 years later."
Using this methodology, we find that most of the effects discussed above are driven by successful assassinations, rather than failures. However, 75% of all assassination attempts fail, and there is some evidence that failed attempts have modest effects in the opposite direction of successful assassinations. In particular, failed attempts slightly reduce the likelihood of democratic change and may lead to reductions in existing, small-scale conflict. Since failures are much more likely than successes, the modest effects of failure and the (less likely but larger) effects of success tend to offset each other. Therefore, from an ex-ante perspective, assassination attempts produce instability in political institutions and the path of conflict – with the outcome dependent on success or failure – but at most modest directional shifts in democracy or war on average.
I don't think there's anything about whether failed assassination attempts make subsequent attempts more or less likely.
With regard to weapons, guns have been the most common instrument, used in 55% of attempts, and explosive devices the second most common, used in 31% of attempts. Guns have kill rates of about 30%, while explosive devices are much less likely to kill the leader, with success in only 7% of cases where the device was actually engaged.
I was surprised that explosives are that much less effective.
Panel A indicates that the annual rate of assassinations increased in the late 19th and early 20th century, decreased substantially during the 1940s (perhaps as a result of heightened security during World War II), and has been at relatively high levels since 1950. Currently, the world witnesses the assassination of a national leader in one of every two years. Interestingly, the frequencies of attempts and successes closely track one another. In fact, the conditional probability of killing a leader given a serious attempt is not trending, remaining at about 25% through time.
That last might be a result of weapons not being improved all that much. Assassinations were more common than I expected.
This means that, although the annual rate of assassinations is currently at historically high levels, the probability that a given leader is killed in any given year has fallen over the 20th Century. At the peak in the 1910s, a given leader had a nearly 1% chance of being assassinated in a given year; today, the probability is below 0.3%.
. First, there is weak evidence that successful assassination attempts, compared to failed assassination attempts, tend to hasten the end of intense wars (i.e. wars with greater than 1000 battle deaths). This effect appears in Panel B, column (1), and suggests that successful assassination lowers the probability of continued, intense conflict by 25 percentage points. Although the effect is quite large in magnitude, it is only marginally significant (P-value of .08 parametrically and .13 non-parametrically) and is not significant when we restrict to the post World War II period. The post-war results are difficult to interpret, however, because there are few observations of intense wars after 1946. Overall we conclude that there is some evidence, but only weak evidence, for an effect on intense wars.
. Second, there is evidence that successful assassination attempts, compared to failed attempts, lead to increased intensity of existing moderate-level conflicts. This is seen in Panel B, column (3), where we see a 33 percentage point increased probability that a war intensifies when the leader is killed. This large point estimate shows some significance (P-value of .05 parametrically and .13 non-parametrically) even though the sample size is substantially smaller due to the fact that the PRIO data exists only for the post-1945 era.
. Third, we find that the outcomes of assassination attempts appear irrelevant to the start of new wars. This is seen in Panel B, across both datasets we examine. For example, taken literally this suggests that World War I might have begun regardless of whether or not the attempt on the life of Archduke Franz Ferdinand in 1914 had succeeded or failed.
Another interesting result that emerges in Table 8 is that attempts are more common in countries with larger populations; doubling the population increases the probability of an assassination attempt each year by 0.35 percentage points. Though this may seem like a small effect, this implies that the leader of a country the size of the United States (population 300 million) is 1.8 percentage points, or about 75 percent, more likely to be assassinated each year than the leader of a country the size of Switzerland (population 7.5 million). This population effect is sustained in a multivariate context, so that it does not appear to proxy for per-capita income, institutions, or war status. One natural interpretation is that the number of would-be assassins rises with a country’s population, whereas there is only one leader in each country.
It seems very reasonable, but not at all obvious.

Link thanks to wedrifid and gwern.

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