Properly interpreted, the DPS data suggests that illegal immigrants in Texas are convicted of homicide and sexual assault at higher rates than the state average.

So write Sean Kennedy, Jason Richwine, and Steven A. Camarota in “Misuse of Texas Data Understates Illegal Immigrant Criminality,” Center for Immigration Studies (CIS), October 2022. DPS is the Texas Department of Public Safety.

Their short report is a critique of earlier work that found lower rates of serious crime among illegal aliens in Texas. One of the studies they criticize is by Alex Nowrasteh of the Cato Institute. (Disclosure: I donate a small amount of money annually to Cato, which gave me my start as a policy analyst in 1979, and I consider Alex Nowrasteh to be a friend.)

Nowrasteh has responded that the three authors made two mistakes in computing the homicide conviction rate for illegal aliens. According to Nowrasteh, they overestimated the numerator and underestimated the denominator. Nowrasteh discusses both in detail. I don’t know enough to judge his analysis of the raw homicide numbers, but he does make a strong case that they underestimated the denominator, that is, the number of illegal aliens in Texas.

Nowrasteh writes:

The CIS crime report uses the second lowest available estimate of the illegal immigrant population in Texas provided by the Center for Migration Studies(CMS), which also produces the lowest nationwide estimate. A lower illegal immigrant population mechanically results in a higher illegal immigrant crime rate by reducing the denominator (assuming the numerator stays the same or increases). Oddly, CIS did not use their own estimates of the illegal immigrant population that they produced elsewhere and instead chose to rely on the far lower CMS population estimates. What’s even more odd about CIS’s choice to ignore their own pure population research on the number of illegal immigrants in their crime paper is that both pieces of research are coauthored by Steven Camarota.

CIS’s own research on the size of the illegal immigrant population in their pure population research paper estimates a nationwide illegal immigrant population of 11,390,000 in 2018 and 11,480,000 in 2019, compared to CMS’s estimate of 10,565,000 in 2018 and 10,348,884 in 2019 – a difference of 825,000 in 2018 and over 1.1 million in 2019. In other words, in its paper focused on illegal immigrant population estimates, CIS estimates a nationwide illegal immigrant population that is eight percent higher than CMS in 2018 and 10.9 percent higher in 2019. Yet, the CIS authors used CMS’ lower illegal immigrant numbers for its paper on illegal immigrant crime rates in Texas. CIS’s pure population estimates imply a Texas illegal immigrant population of 1,940,000 (what DHSfound using the same methods) but CMS found 1,781,752. CIS thus used a population estimate for the number of illegal immigrants in Texas that is 7.5 percent below their pure population estimates in 2018 and 8.9 percent lower in 2019.

He later writes:

In their pure population research, CIS bragged that their estimates of the illegal immigrant population were in line with DHS’s own population estimates. CIS’s pure population research didn’t break out their estimates by state, but DHS did. Since the DHS and CIS methods are nearly identical (they use different data sources), I can use DHS’ Texas‐​level estimates in the following example. CIS’s slightly higher counts of illegal immigrant crime, coupled with with CIS’s pure population research that implies a Texas illegal immigrant population of 1,940,000 in 2018, reveals that illegal immigrant homicide rates are below what Cato’s illegal immigrant population estimation methods would have been if compared to CIS’s crime data (Figure 1). CIS’s pure population research, combined with their illegal immigrant homicide convictions data, produces a homicide rate of 2.9 per 100,000 illegal immigrants compared with Cato’s three per 100,000. Both rates are below Cato’s native‐​born American homicide rate in Texas in 2018.

DHS is the Department of Homeland Security.

You might wonder why the focus on Texas. The main reason is that their data are more finely divided.

See this October 2020 paper co-authored by Alex Nowrasteh for an earlier comparison of various serious crime rates.

Note: I updated this to note that the data are on the homicide conviction rate, not on the homicide rate. HT2 Ross Levatter for pointing out my error.