California, like the rest of the country, suffered a major increase in homicide in 2020. The Center on Juvenile and Criminal Justice (CJCJ) has released a report by Mike Males that presents differences between Republican- and Democratic-voting counties (identified by majority voting Democrat in 2020) in terms of homicide rates. He argues that Republican counties tend to have higher homicide rates, stating that: “the clearest difference between areas that have cut crime substantially and those suffering the worst crime trends and rates is not geographic nor demographic, but how they vote – Republican versus Democratic.” However, this report ignores a number of important variables that could be obscuring this finding. Namely, Republican-voting counties tend to be more rural, suburban, and overall have a lower median income when compared with Democratic-voting counterparts, all of which could also impact homicide rates. The classic phrase to remember here is: “correlation does not equal causation.”
It is perplexing why a researcher would compare two groups that are vastly different from each other without attempting to control for outside factors that might differ between groups, such as geography or population size. As a result, the groups are not entirely comparable because they are not similar enough; in this situation researchers would need to apply adequate statistical controls to account for these differences, something that is missing from this analysis. Ideally, a well-conducted study would attempt to control for all factors that differ between counties, except for the political affiliation, i.e., the main variable of interest. Continue reading . . .