Does the Media Coverage of Mass Shootings Promote new Copycat Crimes

The attached  figure  shows a plot of 7 years of data on mass shootings.

Vertical lines represent the 7 years from 2012 to 2018.   On each line calendar dates are replaced by the number of days into the year. from 1 at the top  to 365 at the bottom.

Mass Shooting events are listed on each line by the day of the year they occurred.

The number 52 at the top of the 2012 line indicates a mass shooting on the 52nd  day of the year or     2 / 21/  2012.

The slanted lines with arrows indicate 14 occasions  where the publication of a one year anniversary  of a mass shooting led to a copycat crime approximately 18 to 30  days later.   This occurred in almost 30% of the mass shooting anniversaries.

source:

Here is a plot of each one year anniversary showing  the length of time to the next mass shooting.   You can see the group
of events from 18 to 30 days.

So what does all this mean.    Perhaps it is just random chance.    Perhaps the 18 to 30 day lag is random.

So lets repeat what we did but first  lets look at the number of shootings in each year.   We get...

Year    Shootings
2012     7
2013     5
2014    4
2015    6
2016    6
2017    11
2018    12

Listed below is random data with 7 events for 2012  5 events for 2013 and so on for each year.

Matlab  was used to obtain random numbers the results are below.

Random Data.

2012         2013          2014           2015

297            200            349            154
331            349            177            334
46              352            292            289
333            58               52            350
231            354                             239
36                                                 13
182                                               310

2016            2017         2018

341            62              160
248            250            139
277            12              279
271            181            298
143            17              68
239            35             179
301           163
254           236
116            275
347            259
13              101
248

Next step is to plot this data.

Note that we have dropped from 14 arrows to 8 arrows.

And then to plot it in a histogram form.

Something is very wrong.     The above plot is what we should  expect if these shootings are truly random.

ARydberg@yahoo.com