As noted in a CJLF press release last month, the FBI's Uniform Crime Reports (UCR) reported a 3% increase in violent crime in 2015 over 2014. Today, the Bureau of Justice Statistics reported that its National Crime Victimization Survey (NCVS) showed no statistically significant change. The lesson here is in the limitations of statistics.
The federal government measures crime in two different ways: the FBI's
Uniform Crime Reports, a nationwide census of crimes known to the
police, and the NCVS, a poll of people 12 and over asking about crimes
committed against them personally.
Each has limitations. The UCR does not capture crimes not known to the police. Sex crimes are severely underreported for obvious reasons. Other crimes may be unreported in varying degrees depending on such factors as whether people think the police will do anything. I suspect that the downgrading of many crimes from felonies to misdemeanors in California will produce a drop in reporting rates, for example.
The NCVS, being a sample, has sampling error, which is why the report speaks in terms of "statistical significance." Sex crimes probably remain underreported, as many victims may be unwilling to discuss such matters with an anonymous voice on the phone. Crimes against victims under 12 are not counted at all.
A difference between the two measures that is always important but particularly so this year is that the NCVS violent crime count "[e]xcludes homicide because the NCVS is based on interviews with victims and therefore cannot measure murder." (Page 2, note a.) The big news when the UCR came out was a nearly 11% jump in murder. See Bill's post of Sept. 26 and mine. NCVS says nothing about that, and when homicide trends are different from trends for other violent crimes the two indexes will diverge somewhat.
Overall, the long slide in crime rates appears to be bottoming out. It may or may not be headed back up nationwide. However, 2015 results in California show a very disturbing uptick, as noted in our press release, and the obvious factor that makes California different from the country as a whole is the much more drastic reductions in incarceration of criminals. It is too soon to claim proof beyond a reasonable doubt of a causal relation, but we have probable cause.
Each has limitations. The UCR does not capture crimes not known to the police. Sex crimes are severely underreported for obvious reasons. Other crimes may be unreported in varying degrees depending on such factors as whether people think the police will do anything. I suspect that the downgrading of many crimes from felonies to misdemeanors in California will produce a drop in reporting rates, for example.
The NCVS, being a sample, has sampling error, which is why the report speaks in terms of "statistical significance." Sex crimes probably remain underreported, as many victims may be unwilling to discuss such matters with an anonymous voice on the phone. Crimes against victims under 12 are not counted at all.
A difference between the two measures that is always important but particularly so this year is that the NCVS violent crime count "[e]xcludes homicide because the NCVS is based on interviews with victims and therefore cannot measure murder." (Page 2, note a.) The big news when the UCR came out was a nearly 11% jump in murder. See Bill's post of Sept. 26 and mine. NCVS says nothing about that, and when homicide trends are different from trends for other violent crimes the two indexes will diverge somewhat.
Overall, the long slide in crime rates appears to be bottoming out. It may or may not be headed back up nationwide. However, 2015 results in California show a very disturbing uptick, as noted in our press release, and the obvious factor that makes California different from the country as a whole is the much more drastic reductions in incarceration of criminals. It is too soon to claim proof beyond a reasonable doubt of a causal relation, but we have probable cause.
You gotta love it when the crime statistic certain to be cited most frequently by the Complacency Crowd excludes -- drum roll! -- murder.
This is another one of those things you can't make up.