Thursday, 19 January 2017

More on the SPLC's hate crime data

Last week, I posted about the Southern Poverty Law Centre's post-election hate crime report. The post showed that Hillary vote share is positively associated with SPLC hate crimes per capita across US states, but is not associated with a measure of hate crimes per capita based on FBI data. This suggests that the SPLC data might have included a non-trivial number of false reports.

However, as Emil Kirkegaard pointed out, the FBI hate crime measure might be invalid itself––i.e., might not be a good measure of the true frequency of hate crimes. To check this, and to further investigate the possibility of false reports in the SPLC data, I obtained two measures of racial prejudice and one objective measure of violent crime. The two measures of racial prejudice are: N-word search frequency (taken from Google), and years with anti-miscegenation laws (taken from the Washington Post). The measure of violent crime is simply the homicide rate, taken from the FBI

Consistent with the claim that the FBI measure is invalid, it was negatively correlated with both measures of racial prejudice, as well as homicide rate. Thus, rather than capturing the true frequency of hate crimes, it probably just picks up state-level differences in how certain crimes are reported. 


However, all three new measures were also negatively correlated with SPLC hate crimes per capita, which calls into question the veracity of the SPLC's data. Results are shown below.


Finally, Hillary vote share is not significantly correlated with any of the three new measures (but is positively correlated with SPLC hate crimes per capita).


Incidentally, homicide rate was strongly associated with both N-word search frequency (r = .61) and years with anti-miscegenation laws (r = .56), but these two variables were only weakly associated with one another (r = .25).

Thursday, 5 January 2017

Were there false reports in the SPLC's post-election hate crime data?

On 29 November, The Southern Poverty Law Centre (SPLC) reported that there had been 867 hate crimes in the United States since the election result was announced. The SPLC's report provided a break down of these 867 hate crimes by state. The authors of the reported noted the following:
The 867 hate incidents described here come from two sources — submissions to the #ReportHate page on the SPLC website and media accounts. Incidents were limited to real-world events; the count does not include instances of online harassment. We have excluded incidents that authorities have determined to be hoaxes; however, it was not possible to confirm the veracity of all reports.
Yesterday on Twitter I came across a plot showing a relatively strong negative relationship between SPLC hate crimes per capita and Trump vote share across US states. (Unfortunately, I can't seem to find the link again, so apologies to whomever made the plot.) In other words, there were more reported hate crimes in states with fewer Trump voters. This suggests that the SPLC might not have been able to exclude all hoaxes or false reports from their data. 

At the suggestion of my friend Roberto Cerina, I investigated this possibility further by comparing the SPLC data to state-level hate crime data from the FBI's Uniform Crime Reports. Specifically, I obtained hate crimes per capita in each state for each year from 2011 to 2015 (as well as Hillary vote share in 2016 for each state). Washington DC was excluded, due to being an outlier. No FBI data were available for Hawaii. 

The correlations between the FBI measures of hate crimes per capita in different years were all very strong, ranging from r = . 78 to r = .92 (p < 0.001 in all cases). This suggests that there is a high degree of persistence in hate crimes per capita from year to year. States with more hate crimes per capita in one year tend to have more hate crimes per capita in the next year. However, the correlations between the FBI measures and the SPLC measure of hate crimes per capita were much weaker, ranging from r = .17 to r = .38 (some significant, some not). Given the high degree of persistence from year to year in the FBI data, I computed the average FBI hate crimes per capita from 2011 to 2015. This variable was correlated with SPLC hate crimes per capita at r = .28 (p = 0.049).

To investigate the possibility of false reporting, I first looked to see whether Hillary vote share or average FBI hate crimes per capita is a better predictor of SPLC hate crimes per capita. Results are shown below:


Consistent with the plot I saw on Twitter, Hillary vote share is strongly associated with SPLC hate crimes per capita. When average FBI hate crimes per capita is added to the model, it enters non-significantly, and Hillary vote share remains a strong predictor. Next, I looked to see whether Hillary vote share is correlated with hate crimes per capita in previous years, as reported by the FBI. Results are shown below:





Hillary vote share is not associated with hate crimes per capita in 2015, 2014, 2013 or 2012. By contrast, the previous year's hate crimes per capita is strongly associated with hate crimes per capita in each year. (It should be noted that there was a marginally significant correlation between Hillary vote share and hate crimes per capita in 2011: r = .26, p = 0.068). In other words, SPLC hate crimes per capita is better predicted by Hillary vote share than FBI hate crimes per capita, whereas FBI hate crimes per capita in any given year is better predicted by the previous year's (or the average) hate crimes per capita.

As an alternative strategy, I regressed SPLC hate crimes per capita on average FBI hate crimes per capita, and saved the residuals. I then plotted the residuals against Hillary vote share (shown below). Note that the residual for a particular state quantifies how many more SPLC hate crimes that state had relative to the number that would have been expected based on previous years' hate crimes (as reported by the FBI). The plot is shown below:


There is a relatively strong positive correlation. In states with more Hillary votes, there were more hate crimes reported by the SPLC relative to the number that would have been expected based on previous years' hate crimes.

Please note that this analysis in no way proves that the SPLC were unable to exclude a large number of hoaxes or false reports, or even a small number. Rather, it is merely suggestive. Comments are welcome, and all data are available upon request.

Tuesday, 3 January 2017

How much room for renegotiation did Cameron have prior to the EU referendum?

Prior to the EU referendum last year, David Cameron attempted to renegotiate the terms of Britain's membership with the leaders of other EU member states. Many commentators (though not all) regarded his renegotiation as a failure, arguing that he achieved very little of substance. It is therefore interesting to pose the question, could he feasibly have obtained more concessions from other EU leaders?

I came across some interesting polling, which suggests the answer is almost certainly not. In February of 2016, Lord Ashcroft polled citizens of all other 27 EU member states. First, he asked them:
As you may know, the United Kingdom will have a referendum within the next two years to decide whether or not to remain a member of the European Union. Would you prefer to see the UK remain a member of the EU, or would you prefer the UK to leave, or does it not matter to you either way?
Results were as follows:


A majority in almost every member state said they would prefer the UK to remain a member of the EU. On average, 60% answered "Remain", 30% answered "Doesn't matter", and only 10% answered "Leave". However, Lord Ashcroft also asked EU citizens:
The UK Prime Minister, David Cameron, is negotiating with the leaders of other EU countries to change the terms of the UK's membership of the EU. Which of the following statements comes closest to your view? It is important that the UK should remain a member of the EU. If the UK does not like the terms of EU membership it should leave.
Results were as follows:


A majority in almost every member state said they would prefer the UK to leave the EU, rather than to renegotiate the terms of its membership. On average, 57% answered, "If the UK does not like the terms of EU membership it should leave", while only 43% answered, "It is important that the UK should remain a member of the EU".