Showing posts with label statistics. Show all posts
Showing posts with label statistics. Show all posts

Sunday, June 26, 2005

Surviving a tour of duty

Josh Marshall and Atrios are both suggesting that young, healthy conservatives who support the war ought to enlist. Marshall's quotes ("Frankly, I want to be a politician. I'd like to survive to see that.") are especially damning.

So, this prompted me to wonder: how big a gamble, exactly, does a person run by enlisting in the military today?

Well, there are about 170,000 US troops deployed in southwest Asia; this includes those in Iraq and Afghanistan, as well as supporting forces elsewhere in the region. There have been about 1,738 deaths and 13,074 injuries since the Iraqi invasion. One might be tempted, naïvely, to conclude that there's about 1% probability of death and 10% probability of injury, but that's not right, because in the 28 months since the March 2003 invasion far more than 170,000 troops have been rotated through Iraq and Afghanistan. Salon's Mark Benjamin reports that "well over 1 million US troops" have gone to war since the initial invasion of Afghanistan. The DoD's casualty reports for Iraq (Operation Iraqi Freedom) and Afghanistan (Operation Enduring Freedom) yield 1,854 deaths and 13,337 wounded. So, naïvely, we obtain 1,854 / 1,000,000 = 0.001854, or about a 0.2% chance of dying.

But that assumes that the probability of death has been constant since the invasion of Afghanistan, which probably isn't the case. Peacekeeping operations in Iraq today, for example, probably have a different casualty rate than the initial invasion of Afghanistan. So, to obtain a better estimate, I use this page's claim that the average tour of duty in Iraq, to date, has been about 320 days, or about 10.5 months. Then I sum the monthly casualty data for the past 12 months (I assume the past year most closely resembles the expected casualty rate over the next year), yielding a total of 876 deaths, or 73 deaths per month. Dividing by the 170,000 serving in southwest Asia in any given month, your probability of dying in any given month will be 0.000429, which means your chance of survival will be 0.99957; raising this to the 10.5 power yields a tour-of-duty probability of survival of 0.9955, yielding a probability of dying over a tour of duty in southwest Asia of: 0.45%.

Of course, this is a pretty crude estimate. If you're an infantryman in Mosul, then your probability of dying will be higher; if you're stationed in Kuwait, then it will be much, much lower. Those who enlist now will probably be sent somewhere in Iraq, where people are most desperately needed. Still, 170,000 troops is a lot, and your probability of being one of the roughly eight hundred who will die during your tour of duty is pretty small.

Now, given the awfulness of the potential outcome, this probability is nothing to shake a stick at, but we should be clear that those who support the Iraq War, but refuse to enlist, are not fleeing from a certain or even likely death sentence. They are fleeing from a combination of hardship and calculated gamble which they have no problem inflicting on others. For the overwhelming majority of US personnel in the Global War on Terror (as the DoD calls it), service to the country consists of a couple years of hard duty and sacrifice, no more --- after which they go back to serving their careers, families, and communities again. I'm not sure whether this makes chickenhawks more hypocritical or less, but there you have it.