How would you answer his SAT-style question?

[Greg Davidson]

I am in an extended debate elsewhere with a very intelligent friend of mine (he was the systems engineering lead on the LCROSS mission and for a few years on the James Webb Space Telescope). But we are at an impasse at a pretty basic level on how to interpret this paragraph from a 2013 government study. I'd like you to read it, then tell me which of two statements best summarize this paragraph:

"Defensive use of guns by crime victims is a common occurrence, although the exact number remains disputed (Cook and Ludwig, 1996; Kleck, 2001a). Almost all national survey estimates indicate that defensive gun uses by victims are at least as common as offensive uses by criminals, with estimates of annual uses ranging from about 500,000 to more than 3 million (Kleck, 2001a), in the context of about 300,000 violent crimes involving firearms in 2008 (BJS, 2010). On the other hand, some scholars point to a radically lower estimate of only 108,000 annual defensive uses based on the National Crime Victimization Survey (Cook et al., 1997). The variation in these numbers remains a controversy in the field."

• the estimated number of defensive uses of guns ranges "from about 500,000 to more than 3 million per year."
• the estimated number of defensive uses of guns ranges from 108,000 to more than 3 million per year.

 

[slipstick]

To quote Wikipedia, "The National Crime Victimization Survey (NCVS), administered by the Bureau of Justice Statistics, is a national survey of approximately 49,000[1] to 77,400[2] households twice a year in the United States, on the frequency of crime victimization, as well as characteristics and consequences of victimization."

What mystifies me is why, since two surveys from 2017 are presumably now available, anyone would cite one of the surveys from 1997? Possibly that was the lowest estimate of the number of annual defensive uses of firearms ever made by the survey, but a figure that old is useless for estimating the frequency of such uses today. According to the NRA, "The first firearms, ca. 1350, called "hand cannons" or "hand gonnes," were essentially miniature cannons designed to be held by hand or attached to a pole for use by individual soldiers." Well, the number of uses of such weapons for defensive purposes in 1300 was presumably zero, since they had not been invented yet, but I doubt that that fact says anything about defensive uses of firearms in the United States in 2018.

Just as a rule of thumb, any estimate on such a controversial and rapidly changing matter more than five years old should be replaced by one more recent. The newer estimate may still be worthless, but any agreement between a 20 year old estimate and present conditions is mostly the result of chance. Not entirely so, of course, as that 1997 estimate suggests the true figure is not over 300,000,000 - or about one per year for every person in the United States old enough to be physically capable of holding a firearm. So it is better than an estimate based on conditions in Italy in 1300, but not enough better to use as a guide to action.

[Fenring]

@ Slipstick, the actually accuracy of the numbers isn't what Greg is asking about. He wants to know the proper textual interpretation of that particular paragraph.

Greg,

Both of those answers are incorrect. The second answer is blatantly wrong because the second method of calculation, which clearly doesn't agree with the first, doesn't place an upper limit, no less one of 3 million. You can combine separate methods of calculation into one combined answer. And citing the majority result as "the summary" of the paragraph would be incorrect as well, since the minority result is listed, and some controversy is mentioned. What it doesn't say is what the source of that controversy is. Is it how to apply the maths? Which type of events should count as a defensive shooting?

In fact, I would suggest that the context of that statement matters a great deal in interpreting the "on the other hand". For instance, let's say the document is from an anti-gun website, and the subsequent paragraph says something like "However, when inspecting these two methods, removing cases of more than one gunshot per encounter, etc etc, the numbers align far more towards the 108,000 figure, thus demonstrating that gun enthusiasts will encourage inflated numbers of defensive gun uses." Not saying that's what the study is meant to show, but if for instance that was the next paragraph, my reading of the one you cite would be:

1. Despite the apparently very high numbers of defensive gun uses, which some estimate to be as high as 3 million per year, other methods (which we will subsequently show to be more honest) show a far lower amount of incidents, closer to 108,000.

After all, why mention that the vast majority all agree with 500,000 - 3 million, and then cite a very different number, if the reason for the discrepancy isn't going to be addressed? Or maybe this would have been the next paragraph (and hence the conclusion):

2. This demonstrates that results in the 'social sciences' are often untrustworthy and can be greatly skewed depending on who's presenting the data and how they obtain their numbers.

Or maybe it's saying something about the field itself in terms of conformity to methods, in which case it might say this:

3. This demonstrates that since a few independent researchers achieves a wildly lower result, that the majority must all be employing the same method as each other. We can see from this that the majority of research consists of copying orthodox methodology with the same set of assumptions, which naturally will lead to similar results.

There are so many other possible interpretations. But I know what you were getting at, Greg, and if you don't want to look at other context then this is what you'd have to conclude:

1. The estimated range is most likely 500,000 to 3 million, with the small possibility that this number is inflated due to methodological error.

[D.W.]

Fenring makes some good points but I think the answer is #2.  If you are trying to make sense of what the actual number of DGU is from the paragraph, then see Fenring's post.  If your friendly debate is simply reading comprehension...  Then 2 is inclusive of 1, and 1 alone has to ignore some of the data provided.  And my resume of smart stuff is not nearly as impressive as your friend. 

[TheDrake]

Defensive gun use is notoriously difficult to pin down.

According to just this paragraph, it is quite easy to say that estimates follow the full range of any number put out from any source. or (b)

[Fenring]

PS - my first paragraph to Greg should read as "You can't combine separate methods of calculation into one combined answer."

Just as a clarification on that point, and why I feel it's wrong to combine the two answers, is because incompatible methods have no relation to each other. For instance, if someone is calculating the area of a circle and using pi(r^2), and the next guy is using pi(d^2), it would be wrong when parsing between these two different results to just average them out and say that that's probably the real answer. Or in a softer application of maths, if I'm counting gunshots fired into the air, and the next guy is only counting gunshots with intent to injure/kill, adding my number, which is no doubt higher, to the upper limit of the second method doesn't represent a new and more inclusive result. It's just a wrong thing to do and any validity either calculation ever had gets lost in the process.

[TheDrake]

I disagree, and also agree.

Surely, three different studies can define "Defensive Gun Use" differently and arrive at different answers, just like different studies on "Depression" might set different standards. With academic rigor, you can't rightly combine the two data sets without making adjustments.

Qualifying the answer might include descriptions of where studies differ, or how they arrived at the estimates, but nevertheless on a broad view there are indeed estimates ranging broadly.

This is why twitter-like statements are inadequate for summarizing a complex data set.

The full quote from the book includes information casting doubt on the upper range of 3 million also. That 3 million number combined data from more than 19 national surveys, according to the text, so even the first part is an amalgam of methodologies.

[Seriati]

As an SAT question, you'd clearly have to answer 2.  It happens fairly frequently, that an incorrect or misleading answer is the "correct" option based on a reading selection.  It's a reading comprehension section, not a general outside knowledge section.