Thursday, May 18, 2017

How is Washington DC an outlier? Let's count the ways. (Repost from Data Driven Journalism)

My latest post on Data Driven Journalism is up an reprinted here.
In my last post, I reported that Washington, DC had an extremely high rate of 30.83 hate groups per million residents in 2016 relative to the other 50 states (the national rate was 2.84 groups per million).  DC also had an exceptionally low percent of the vote for Donald Trump in 2016, at just 4.1%.  For these reasons, and other characteristics which make DC fundamentally different from the other 50 states, I had to exclude it from a correlational analysis between hate group concentration and Trump’s percent of the vote.  For this post, I will look at other ways in which DC is an outlier.

According to the most recent Small Area Income and Poverty Estimates (SAIPE) from 2015, DC ranks third in median household income at $70,848 behind Maryland and Alaska. Yet, the same SAIPE estimate also ranks DC eighth for the percent of the population in poverty, at 17.4%.  This indicates a large gap between the rich and poor.  The high rate of poverty is reflected in DC’s low life expectancy at 76.53 years, ranking 43rd compared with the overall US average of 78.86 years. Similarly, DC’s infant mortality ranked eleventh in the country, at 7 deaths per 1,000 live births compared to the US rate of 5.9 deaths per live births.  Newly released estimates from the Census Bureau for 2015 show DC has the second lowest rate of those without health insurance at 4.3% behind Massachusetts. These income and health statistics suggest that DC deviates from the national rates, but not that it is an extreme outlier – with one exception.

The statistics on crime suggest that DC is an extreme outlier.  DC had a violent crime rate of 1,244.4 offenses per 100,000 residents in 2014.  This is almost twice as large as the next highest state, being Alaska with a rate of 635.8 offenses per 100,000 residents, and more than three times as large as the US rate of 365.5 offenses per 100,000 residents.  In 2014, it had the highest murder rate of any other state at 15.9 offenses per 100,000 residents. 

Image: Paul Ricci.
Last fall, the FBI’s Uniform Crime Report released the number of hate crime incidents in 2015 for each state.  Adjusting their numbers for population, DC had a higher rate than any other state, at 96.69 offenses per million residents. Using the FBI rate method, this rate would be 9.67 reported offenses per 100,000 residents.  As the above graph shows, this hate crime rate corresponds with DC’s high rate of hate groups.  However, this relationship does not hold up when DC is excluded from the analysis, as can be seen in the graph below.  If DC is excluded, there is no statistically significant relationship between the concentration of hate groups and hate crimes in any of the other states, with only 2% of the variability accounted for.

Image: Paul Ricci.
Comparison of DC with New York City

So what factors besides poverty could be driving this relationship?  Compared to the other states DC has the highest population density by far at 11,157.58 persons per square mile.  Because Washington, DC is a quasi-city state, it may be appropriate to compare it to the US’s largest city, New York City (NYC).  In 2015, NYC had 8,550,405 inhabitants over a total of 302.64 square miles (approximately 488.13 km2) giving the city a population density of 28,252.72 persons per square mile.  I don’t have hate crime data for NYC but I can estimate the hate group rate from the hate group map of the Southern Poverty Law Center.  I counted 36 hate groups in the area, which would give NYC a rate of 4.21 groups per million – a number which is considerably below DC’s rate of 30.83 groups per million. In 2010, 25.5% of NYCs population identified as African-American whereas 50.7% of DCs population did.  Of the 21 total hate groups in DC, six of them are black separatist groups such as the Nation of Islam (28.6%).  Of the 36 hate groups in NYC, eight are black separatist (22.2%).  You can scan the other hate groups in each city here.

Looking at other statistics for NYC, the violent crime rate is 596.7 offenses per 100,000 residents and the murder rate sits at 3.9 offenses per 100,000 residents.  These are considerably lower than DCs rates of 1,244.4 violent offenses per 100,000 residents and 15.9 murders per 100,000 residents.  DC has a higher median household income at $70,848 than NYC’s $53,373.  Correspondingly, the 20.0% poverty rate for NYC is higher than DC’s 17.4%. 

One must be careful to draw grand conclusions from statistics that compare DC to the rest of the US and DC to NYC.  One can look at the obvious differences DC has with the other states. While it has three votes in the Electoral College for President, it has no members in Congress with full voting privileges on laws which may affect them. Further, as John Oliver explains, they have to pay full federal taxes:

We see Washington, DC portrayed in the media all the time but do we really notice what goes on there outside of the White House, the Capitol Building, and the various other federal buildings?  DC residents have been campaigning for full statehood for years but it has been stalled in Congress.  This second class citizenship may or may not explain all of the statistical discrepancies for DC.  The issue definitely merits further study.  There could be many other anomalies regarding DC of which I am not aware.

**Related Posts**

Don’t test me: Using Fisher’s exact test to unearth stories about statistical relationships (Repost) 

Concentration of Hate Groups Predict Hate Crimes (if you consider DC) and Trump Vote (if you don't)

SPLC Hate Group Update: Washington, DC has an Increase in Activity