Deltoid

kebarnes writes:

Are Kleck's numbers concerning the self-reporting of robbery and burglary incidences from this survey out of line with the comparable NCVS results, for instance? Rs to Kleck's survey reported that 5.5% (274/4977 Rs) had been a burglary victim within the past year, and 2.5% (124/4977 Rs) had been a robbery victim within the past year. This would imply (if I'm correct) some 242,600 robberies and 533,800 burglaries.

You dropped a decimal: it's 2.4 million robberies and 5.3 million burglaries. And 500,000 (20%) of robberies where a gun was used for defence. And 850,000 (16%) of burglaries where a gun was used for defence. That last percentage is especially remarkable. With only 14% of burglaries occupied ones and 50% of US households having guns a generous upper bound on the percentage of burglaries where a gun is used for defence is 7% which is considerably less than 16%.

How does this square with other sources for 1993?

According to the 1992 NCVS figures (the latest available to me), the percent of households reporting a burglary in the past year was 4.2%, and the percent of households reporting a robbery in the past year was 1.0%. An approximate ratio for burglaries to robberies in 1993 according to the FBI's Uniform Crime Reports is about 3.7 to 1, which isn't substantially different from the NCVS reporting (if you exclude robberies and burglaries of commercial buildings and banks, which Kleck's Rs are unlikely to report). If the NCVS numbers on the incidence of burglary and robbery are reliable, then there might be some argument for 'telescoping,' but this depends whether these differences are within the sampling error of the survey.

A 95% confidence interval for percentage burgled is 4.5%-6.7%, for percentage robbed it is 1.8%-3.4%, so the difference are not within the sampling error of the survey. (In case anyone wants to check my calculations, the sample size was 1660 not 4977 since the full questionnaire was only given to 1/3 of Kleck's respondents.)

Another way to estimate DGUs is to ask criminals how often they were thwarted by armed victims. This is what Wright & Rossi did. 34% of the criminals that they surveyed admitted this. These criminals had an average of 10 prior arrests, so if the 34% who had been thwarted had an average of two thwartings each, it would appear that being arrested is roughly 15 times as likely for these criminals as being stopped by an armed victim. Combine this with about 988,000 arrests per year (this number from Kleck's "Crime Control" paper) and we get a (very rough) estimate of 70,000 crimes stopped each year with guns. The uncertainties in this calculation are large: it might be off by a factor of two or three, but a factor of thirty is implausible."

Lambert's really grasping at straws with this analysis, since he's making the assumption that the criminals who are actually incarcerated are not only a representative sample of the criminals involved in DGUs with victims,

No, I'm assuming that criminals involved in a DGU are no more than two or three times less likely to be imprisoned. Is it your contention that a DGU makes it LESS likely that the criminal will be captured?

but are honest enough to admit to something which would be personally embarrassing to them.

They seem to have admitted to a bunch of other embarrassing things. Maybe 50+% of Wright and Rossi's respondents lied. Maybe 4% of Kleck's lied. Take your pick.

What gets me is that Kleck actually cites the 34% statistic as SUPPORTING his study when in fact it contradicts it!

He's also assuming that criminals who are arrested (using Kleck's 988,000 figure) are representative of the criminals involved in DGU incidents with victims, or are anywhere near a reasonable estimate of the number of actual violent crimes attempted each year.

You are confused. The comparison is based on often these criminals were arrested versus how often they faced an armed victim.

We can based on the number of violent crimes if you prefer: They averaged 50 violent crimes each in their careers versus .67 times they faced an armed victim. That's 75 to 1. Dividing 10 million violent crimes by 75 gives an estimate of 130,000 DGUs. Again, nowhere near Kleck.