analysis: homicide

On Homicide in the Greater Boston Area

I know someone who doesn’t feel safe taking public transit or walking alone at night. I feel perfectly safe doing these things and, generally, prefer them over cabs. Maybe I lack the visceral fear some people develop as a result of being catcalled within the city. Maybe I grew up in a (more) dangerous place, and am left generally unfazed by suburban feel of Camberville. Regardless of the reason, I don’t worry about being spontaneously raped, mugged, or shot while out.

This is about homicide.

Homicide refers to the killing of a human–as manslaughter or murder. It also includes “justifiable killings.” The FBI only includes non-negligent killings and murder.


National rates are gathered from CIUS (Crime in the US, link below), which is maintained by the FBI, and the Disaster Center. The CIUS national numbers are from 2011 and 2012, the CIUS state numbers are from 2012 and 2013. Disaster Center numbers are from 2012 and 2013.

Homicide – National

Source Years Population per 100k total
CIUS 2011 311,587,816 4.7 14,661
CIUS 2012 313,914,040 4.7 14,827
Disaster Center 2012 313,873,685 4.7 14,752
Disaster Center 2013 316,128,839 4.5 14,196


For these numbers, I took the national rate per 100k (homicides per 100k people), and estimated based on the population [(population/100,000)*homicides per 100k] The CIUS number comes from only urban areas within MA. The Disaster Center numbers are from the entire state.

MA – Estimates Based on National Averages

Source Years Population per 100k total (estimated)
CIUS* 2012 1,183,933 4.7 55.64
CIUS* 2013 1,192,220 4.7 56.03
Disaster Center 2012 6,645,303 4.7 312.33
Disaster Center 2013 6,692,824 4.5 301.18

MA – Actual

Source Years Population per 100k total
CIUS* 2012 1,183,933 3.04** 36
CIUS* 2013 1,192,220 3.61** 43^
Disaster Center 2012 6,645,303 1.82** 121
Disaster Center 2013 6,692,824 2.05** 137

*Urban areas include Boston, Cambridge, Lowell, Springfield, and Worcester

**Maths done by me. For generating the per 100k, when the number was [(population/total homicides)*100,000].

^Four of these (9.3%) are related to the Boston Marathon Bombings.

We’re doing pretty well compared to the national average.

Local Numbers

These are about Boston, Cambridge, and Somverille. There are gaps. I left open the population totals (when they were not listed on the corresponding website) because I don’t know where they got their numbers from and, as you can see, their other numbers differ.

Boston, Cambridge, Somerville – Estimates Assuming National Rates

Source Years Population per 100k total
City Data – Boston 2011 N/A 4.7 N/A
City Data – Boston 2012 636,479 4.7 29.91
City Data – Cambridge 2011 N/A 4.7 N/A
City Data – Cambridge 2012 106,471 4.7 5.00
City Data – Somerville 2011 N/A 4.7 N/A
City Data – Somerville 2012 77,104 4.7 3.62
CIUS – Boston 2011 630,648 4.7 28.38
CIUS – Boston 2012 N/A 4.7 N/A
CIUS – Cambridge 2011 106,981 4.7 5.03
CIUS – Cambridge 2012 N/A 4.7 N/A

Boston, Cambridge, Somerville – Actual

Source Years Population per 100k total
City Data – Boston 2011 N/A 10.1 63
City Data – Boston 2012 636,479 9 57
City Data – Cambridge 2011 N/A 4.7 5
City Data – Cambridge 2012 106,471 0.9 1
City Data – Somerville 2011 N/A 0 0
City Data – Somerville 2012 77,104 0 0
CIUS – Boston 2011 630,648 3.65** 23
CIUS – Boston 2012 N/A N/A N/A
CIUS – Cambridge 2011 106,981 0.93** 1
CIUS – Cambridge 2012 N/A N/A N/A

**Maths done by me, see above.

Thoughts, Additional Table, Disclaimers, etc

City Data and CIUS have really radically different numbers. City Data does provide a disclaimer saying that their information may be neither accurate nor timely. They suggest using “at your own risk.” Comparing Disaster Center and CIUS is not really worthwhile, as they consider different populations.

It’s really sad that Boston’s crime rates are higher than Camberville’s.

The FBI’s Uniform Crime Reporting (UCR) has a program called National Incident-Based Reporting System (NIBRS) This is a very specific type of reporting system, which provides very different data than the above. Starting in 2011, data previously managed by UCR was replaced with NIBRS.

Homicides: NIBRS, UCR

Source Years Population Homicides
NIBRS 2013 316,128,839 3,465
UCR (National) 2010 308,745,538 14,748
UCR (MA) 2010 6,547,629 210
UCR (Boston) 2010 617,594 73
UCR (Cambridge) 2010 105,162 0
UCR (Somerville) 2010 75,754 0

In their pamphlet, NIBRS says that only 19% of homicides in 2013 were committed by a stranger. In terms of a random person killing me on the street, I’m not worried. In Camberville, over the past few years, there was only one stranger on stranger homicide and it was far beyond what one worries about when they think about being killed randomly.

Given infinite time and resources, it would be interesting to pull up each of the specific cases of homicide in Camberville (which is very doable).

I don’t know anything about statistics beyond folk knowledge and the things you learn in bio lab and from your statistician friends. That is to say: more than the average person on the average (i.e. non-Camberville) street, but not really a lot. My maths are based on what I know: public education and intuition. I am happy to receive criticism, advice, and corrections.

I know that there are lots of crimes other than homicides that are problems. Sexual assault is huge. Writing about homicide took me so long, I decided to shelve sexual assault until a possible future.


CIUS – National is maintained by the FBI. They use the term “murder and nonnegligent manslaughter.”


Disaster Center uses the term “murder.”

Disaster Center – National

Disaster Center – MA

City Data uses the term “murder.”

City Data – Boston

City Data – Cambridge

City Data – Somerville

Uniform Crime Reporting

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