UPDATE: We have added ChatGBT’s evaluation of the post below.
Original Post: Despite what the media and the Bureau of Justice Statistics are noting, if you look at the percentage changes in crime rates under the Biden administration, there has never been such a large increase in serious violent crimes (rape, robbery, and aggravated assaults). Indeed, nothing even close. Outside of the 55.4% increase in 2023 over 2020 and the increase in 2022, the next largest increase was the 27% increase in 2006 over 2003. And that increase in 2023 is extremely statistically significant. While researchers might use significance levels at the 5% or 10% level, these percentage changes from 2020 to 2023 or from 2019 to 2023 are significant at better than the 0.0001% level. The same is true if one includes simple assaults, which are misdemeanors.
The Bureau of Justice Statistics redesigned the Bureau of Justice Statistics the National Crime Victimization Survey in 1992, so we initially focus on numbers examined here for the years 1993 to 2023. We discuss the earlier data that goes back to 1973, though at the moment, we only have access to raw data that includes misdemeanor simple assaults. At the end of this post, a graph is provided for serious violent crime. The largest three-year increase in serious violent crime during the 1973 to 1993 period appears to have been 20% between 1990 and 1993 (based on trying to determine the values from the available graph), which is just 36% of the 55.4% increase between 2020 and 2023.
UPDATE: Friday, the Associated Press put out another attack on Trump’s claims about crime.
CLAIM: New numbers show that crime has skyrocketed under the Biden administration.
THE FACTS: Violent crime surged during the pandemic, with homicides increasing nearly 30% in 2020 over the previous year — the largest one-year jump since the FBI began keeping records.
But FBI data released in June shows that the overall violent crime rate declined 15% in the first three months of 2024 compared to the same period last year. One expert has cautioned, however, that those figures are preliminary and may overstate the actual reduction in crime.
On Friday, Trump cited numbers he said were from the “bureau of justice statistics” to claim crime was up. This appears to be a reference to the National Crime Victimization Survey recently released by the Justice Department, which shows that the number of times people were victims of violent crime increased by about 40% from 2020 to 2023. The report notes, however, that while the rate of violent victimizations in 2023 was higher than it was in 2020 and 2021, it was not statistically different from the rate in 2019, when Trump was president.
Melissa Golden, “FACT FOCUS: A look at false claims made by Trump in California,” Associated Press, September 13, 2024.
The AP was relying on this statement from the Bureau of Justice Statistics.
“While the 2023 rate was higher than those in 2020 and 2021, it was not statistically different from the rate 5 years ago, in 2019,” Kevin M. Scott, Ph.D., BJS Acting Director.
Bureau of Justice Statistics, “Violent victimization unchanged year over year and at prepandemic levels,” U.S. Department of Justice, Office of Justice Programs, September 12, 2024.
- The increase from 2020 to 2023 in violent crime (rape, robbery, and aggravated assaults) was 55.4%. That is the largest percentage increase in violent crime over any three years recorded by the NCVS. The increase from 2019 to 2023 was 19.2%, the second largest increase in violent crime over any four years by the NCVS. The largest increase was in 2006. Excluding simple assaults (which is a misdemeanor) includes the same violent crimes included in the FBI measure of violent crime since they only include felonies. If you use the data with misdemeanors, the change from 2020 to 2023 was 37.2%, and from 2019 to 2023, just 7.1%. The 7.1% increase is much smaller than the 19.2% increase in felonies. Understandably, people will focus on the large percentage increases in felonies.
- Trump stated that crime increased under the Biden administration. Golden responds by saying the change from 2019 (using the misdemeanor numbers was up) was not statistically significantly different from 2023. The percentage increases were statistically significant, using the crimes analogous to the FBI’s violent crime data.
- The “Three Years Differences” variable compares the percent change from 2020 to 2023 to all the other three-year changes in the NCVS data. The “Four Year Difference” compares the percent change from 2019 to 2023 to all the other four-year changes in NCVS data. The first two estimates look at the total violent crimes for rape, robbery, and aggravated assault. The second two estimates look at the total violent crimes for rape, robbery, aggravated assault, and simple assault. The percentage crime rate increases during the Biden administration were all statistically significant, at least at the 0.0001 percent level, for a two-tailed t-test. These comparisons were made, removing the value for 2023 from the comparison sample, but the results are unchanged if the year values we are comparing to the rest of the sample are included. The STATA data file is available for download here.
4. Here are the tests of statistical significance that combine the original and revised NCVS for violent crime with misdemeanor assaults. So, these results cover the period from 1973 to 2023.
5. While it is obvious why Americans might focus on the percent changes instead of the levels, over the last twenty years, even looking at the levels, the increase in violent felonies between 2020 and either 2022 or the last two years of the Biden administration was statistically significant at the 7% level. There were large drops in crime levels during the 1990s but no increases. However, including those large drops in the levels, because they are such large drops, makes it more difficult to find that the rise is statistically significant. Finally, while there was an increase from 2019 to the last two years of the Biden administration, it wasn’t statistically significant whether one looks at the last twenty years or includes the drops during the 1990s.
Earlier NCVS data. For the earlier NCVS serious violent crime data, we have been only able to recover a graph of that earlier data (the BJS claims that they don’t have a copy of the original raw data because it wasn’t kept when they migrated computer systems), and the data graph hasn’t been adjusted to make it compatible with the new version of the NCVS, but it shouldn’t be a problem if one is comparing the percentage changes from one year to another. Given that, these graphs are suggestive, but it appears that the largest three-year increase over that period occurred from 1990 to 1993. If that increase were from 3.5 to 4.2 offenses in millions, that would be a 20% increase. Even if it were from 3.5 to 4.3, that would be a 23% increase.
Unfortunately, the BJS made adjustments to the data in 2011, but that adjustment was only applied to the data from 1993 to 2023 (because they lost the data when they migrated computer systems), and the size of the adjustment varies over time, so there is no simple way that the adjustment can be applied to the earlier data from 1973 to 1992. A discussion of their adjustment in 2011 is available here.
UPDATE: We couldn’t feed the screenshots of our statistical results to ChatGBT, but here is ChatGBT’s evaluation of the above post. You can check this evaluation by feeding our post yourself.
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