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    Don Stemen

Using homicide data in class

Posted on: January 17th, 2013 by Don Stemen

Several topics are likely dominating the first week of most criminal justice and criminology classes this semester. Following the shooting in Newtown, CT, there are certainly discussions of gun violence and the effectiveness of specific restrictions, such as prohibitions on the sale of assault rifles and high capacity clips, in preventing such violence.  In turn, there are likely discussions about the relationship between mental illness and crime and the obligations of mental health professionals in identifying and responding to individuals who pose a risk to public safety.  Following changes in state responses to drug offenses in Colorado and Washington, there may be discussions about the legalization of drugs or the decriminalization of possession of certain drugs.  Following the suicide of Aaron Swartz, there also may be discussions of prosecutorial discretion and evolving definitions of hacking and internet crime.

Dr. David Olson and I relied on another topic — homicides in Chicago — to illustrate several different points across different courses.  In fact, we used the same few charts (created by Dr. Olson) to illustrate 1) how the media creates perceptions of crime (in CRMJ 101 – Introduction to Criminal Justice), 2) how the debate about a homicide trends in Chicago may be framed (in CRMJ 399 – The Criminal Justice and Criminology Capstone), and 3) the different ways the same statistic may be interpreted to reach vastly different conclusions (in CRMJ 404 – Applied Data Analysis and Interpretation).

Here was the first chart, showing the number of homicides in Chicago in 2011 and 2012.

As the chart shows, homicides in Chicago increased by roughly 17% last year, from 433 homicides in 2011 to 506 homicides in 2012.  This was not an insignificant increase — it equates to roughly 6 homicides every month or 1.3 homicides every week.  And when we discussed this with students in class, they naturally recognized this increase dramatic — which it is.  In the CRMJ 101 course and the CRMJ 399 course, I asked students if the number of homicides indicated a serious problem for Chicago in need of a significant, immediate response.  And most said, “Of course.”

Here is the second chart we showed them, showing the number of homicides in Chicago since 1985:

As the chart shows, homicides in Chicago in 2012 were significantly lower than they were at their peak in 1992 — in fact the number of homicides in 2012 was nearly half the number that occurred in the early 1990s.  In the CRMJ 404 course, Dr. Olson used these two slides together to demonstrate how careful we must be in presenting simple descriptive statistics; a more pessimistic take-away may be that we can manipulate perceptions of a topic depending on which way we want to present the same statistic.  IN CRMJ 101 and CRMJ 399, I used these two slides to encourage students to question both how this topic is presented in the media and how their own perceptions of the topic are formed.

These exercises were not meant to minimize the extent and nature of homicides in Chicago.  In fact, I followed these slides by showing an excellent map of homicides and shootings in Chicago compiled by the Chicago Sun-Times at  By selecting certain neighborhoods in the map, one can see how homicides and shootings were heavily concentrated in a few neighborhoods in the city — in these neighborhoods, violence remains an all too common part of life.

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