Friday, January 1, 2016

Murder Rates: Depends on where You Measure

When I hear about city murder rates, I always wonder whether that refers to the city proper, or the greater metro-area. City murder rates are usually higher because suburbs tend to be safer. But city borders can be arbitrary- when considering two similar metro-areas, one city could have larger borders, which then makes it appear safer because it includes more suburban-type neighborhoods. To help clear this up, I used FBI data to graph the city murder rate versus the murder rate for the entire metropolitan statistical area (MSA):



New Orleans is the clear outlier. Detroit, Baltimore, and St. Louis have similarly high murder rates in the city, but New Orleans has a uniquely high murder rate for the MSA. The murder rate for the greater metro area of New Orleans is about as high as the city of Memphis or Atlanta (unlabeled).

The trend line shows the average relationship between the city rate and the MSA rate. Virgina Beach is noticeably above the trend line, but that is because the Virginia Beach MSA is a combination of multiple cities, including the less-safe Norfolk and Newport News, unlike most other MSAs which tend to be a single large city and surrounding suburbs. 

In each case, the largest city by population in the MSA is graphed, and only MSAs with at least a million residents are included.

The same graph is reproduced below as an interactive, which provides hover text for unlabeled cities:



The relationship between city murder rate and MSA murder rate is fairly strong (R square = 0.57). But this is at least partly driven by the inclusion of city rates in the MSA rate. The graph below shows city rate and the non-city rate- the MSA rate minus the murders and population from the city.



Notice there is almost no relationship between city murder rate and suburb murder rate (R Square = 0.02).

Cities lowest on the graph and to the left have the safest suburbs relative to the city. Milwaukee's murder rate is the most segregated along city borders- a person in the city is 28 times more likely to be murdered than a person in the metropolitan area outside of the city.

*Some MSAs did not have all member cities/municipalities report crime data. In these cases, I used the FBI's estimated totals. All cities had reporting for at least 94% of their population, with the exception of Indianapolis (86%).

10 comments:

  1. John, I am trying to contact one of the top authors on Tableau about getting on viz of the day but it is tough to find contact information for you two. Please e-mail me at cdjohnson013@Gmail.com or check out my viz at
    https://public.tableau.com/profile/clinton.johnson6689#!/vizhome/LeagueofLegendsStronkestADCs2/Dashboard1
    Thanks, and sorry for the plug but I'm honestly just trying to get a contact point

    ReplyDelete
    Replies
    1. Thanks Clinton. I'm not familiar with League of Legends, but it looks like a cool way to use Tableau to understand one of your other interests. You can find me on twitter @keltz_, or contact me on email- john.keltz at gmail.

      Delete
  2. Kingoroot App is very popular android rooting tool which is based on Windows And Android 
    kingoroot for pc

    ReplyDelete
  3. Grammy 2017 will be at 5:00 PM - 8:30 PM on Sunday, February 12, 2017 in Los Angeles at the Staples Center. Read more:



    Grammys

    Grammy 2017

    Grammys 2017

    2017 Grammys

    Watch Grammy 2017

    Grammy Awards

    Grammy Awards 2017

    ReplyDelete