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On Tuesday night, citizen hackers, urban planners, data scientists and others funneled into a crowded conference room to talk about data.

The meeting, held every Tuesday at 1871, a working space on the 12th floor of Chicago’s Merchandise Mart, allows civic-minded individuals from all walks of life, including developers to network and find ways of producing applications utilizing civic data.

They might have also piled in to hear Rayid Ghani, the former chief data scientist of the Obama 2012 campaign, explain how to use social networks and analytics to get the broadest reach for your organization. But also: data!

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By Elliott Ramos

Chicago Transit Authority president Forrest Claypool had some biting words for the Chicago Sun-Times — on its own pages.

On Thursday, the CTA chief penned a letter to the editor, chastising the newspaper’s article on CTA crime that ran on Tuesday.

On Monday evening, the tabloid released an article online, utilizing data analysis about CTA crime.  The front page of its Tuesday print edition ran with the headline: HIDE YOUR iPHONES.

Monday evening, the CTA countered with a release criticizing the analysis as flawed. The CTA’s main point of consternation was the Sun-Times claim of a 21 percent increase in crime.  

The sub-headline of the front page story read: “CTA rail stations hit by 21% spike even with high-tech surveillance.”

In his letter, Claypool said the suggestions are “false and misleading.”

The CTA did not refute whether or not crimes actually happened, but rather what types of crime should be measured and how they were measured.

The premise of the story is that crime increased on or around CTA rail stations despite an increased use of security cameras from 2010 to 2012.

In order to determine that, reporters had to assess which crimes happened near the cameras. The methodology that defined which numbers were used is at the heart of why the CTA says one thing and Sun-Times said another.

Given WBEZ’s commitment to data reporting that helps Chicagoans make sense of their city, we’re hoping to demystify the numbers… with a hilariously long-winded post on data.

The CTA crime story has made its way from online and print to subsequent TV reports.

And before sheer repetition turns this story’s claim into a commonly accepted idea among Chicagoans, we decided to look a little closer at the numbers.

If you don’t want to get into the weeds of data, numbers and variables, then the gist is this:

  • The Sun-Times analysis weeded out more than half of the locations identified as CTA crime to account for areas with cameras, although excluded buses, which all have cameras. It also excluded trains (which are partially fitted with cameras.)
  • Sun-Times also factored in all crime. CTA says violent crime is down. (Although some batteries are actually up.)
  • Theft overall is up because of smartphones, but the problem is not unique to CTA or Chicago. It’s a nationwide trend given the ease of stealing a small, expensive device.
  • The analysis does not take into account ridership numbers, which could vary dramatically depending on time of day.

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