US Mass Shootings 2013-2015: Geo and Temporal Distributions

US mass shootings have been a society problem for quite some years. Gun violence is a problem that is particular in the US where we have the best of technology and thinkers, but we don't know what to do with the guns.

Here is an effort to understand the distribution of mass shooting incidents. Mass shooting is defined as an incident where 4 or more people got shot, whether killed or wounded. The study will lead us to gain certain insights into the pattern of the problem.

The data set is from Shooting Tracker which is now merged with Gun Violence Archive.

Temporal Distribution

We have performed weekly, monthly and quarterly aggregations of the incidents. The insights are quite obvious:

- Weekend incidents are way more than working days. Saturday ~2x more. Sunday ~3x.

- Summer months may witness more mass shooting incidents.

- Q3 is the highest in the number of incidents.

Geo distribution

We used quartile-based approach to analyze the distributions.

By using quartiles along longitude, we see that 75% of events are in the Eastern part of the US.

By using quartiles along longitude first, followed by latitude quartiles within each longitude quartile, we get 16 contiguous area of equal number of incidents. In other words, we created 16 quantiles. Then we calculate the size of each quantile and use the size value (actually using LN(size)) to create a reverse heatmap. Now we see right away that the metropolitans of New York and Chicago are the highest in incidents density.

That's the research result of lately. Feel free to improve it and comment on it.

Click the above image to view the interactive version and download the workbook.

There are other Tableau visualizations on the incidents from different angles:

Dash Davidson

https://public.tableau.com/s/gallery/2015-us-mass-shootings

Andy Kriebel

http://vizwiz.blogspot.com/2015/11/americas-gun-problem-how-frequently-do.html

Michael Mixon

http://mixpixviz.blogspot.com/2015/12/mass-shootings-in-2015.html

(Refresh the page if you want to view the gif image multiple times. Or go to Tableau Public and click the button at the top-right corner.)

Jake and I collaborated on a dashboard. He told me that he learnt a way to create an in-place help page in Tableau. He first saw it at a conference somewhere and couldn't recall who the speaker was. So I am blogging here about it but the credit goes to somebody else. If anyone knows who the original creator is, leave a comment below.

The key idea is to float a semi transparent worksheet on top of the dashboard, where a help text box is strategically placed on top of each chart. This way, we can explain how to view each chart and what data points are important, etc. This worksheet is collapsible by a show/hide button.

Below I would like to show how this worksheet can be constructed.

1. Sheet with a single data mark.

Double click the empty space in Marks panel and add two single quotes. Make the null pill a text label. This creates a single null mark.
Set the view as "Entire View"

2. Create an show/hide button

Go to the target dashboard
Drag a floating vertical container to the dashboard, making it cover all the area of interest.
Drag the Single Null Mark sheet and drop it into the above container. Hide the sheet title.
Create an open/close button for the container and place the button at the top-right corner.

3. Add annotations

Format the sheet background opacity as 70% in the layout manager
Select area annotations and place them anywhere of interest.
Write help text and format it to highlight important messages.
The text can serve as functional guide and/or insight guide.

Here is an example. Feel free to download the workbook and explore. Click the "i" button at the top-right corner to view the in-place help.

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Vizible Difference

In search of data visualization excellence

1. Sheet with a single data mark.

2. Create an show/hide button

3. Add annotations

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