Just reading their report quickly, it doesn't look like they're controlling for a lot of things, and are measuring non-target cultural factors which skew their correlation. (Of course, they don't even mention their methods, because it likely would be such an obvious source of criticism with their conclusion.[1])

Which isn't to say I'm right either, and certainly raises a bigger question about it, but back to my point: we just can't tell, because there is a lack of detail in their analysis.

[1] http://mappingpoliceviolence.org/2015/

Their methods are listed under the "about the data" tab, which links to http://mappingpoliceviolence.org/aboutthedata/ :

> This information has been meticulously sourced from the three largest, most comprehensive and impartial crowdsourced databases on police killings in the country: FatalEncounters.org, the U.S. Police Shootings Database and KilledbyPolice.net. We've also done extensive original research to further improve the quality and completeness of the data; searching social media, obituaries, criminal records databases, police reports and other sources to identify the race of 91 percent of all victims in the database.

It also lists their definitions for "police killing", "unarmed", "vehicle", and "allegedly armed."

They also make the data available for download, so you can verify it. The columns are:

  Victim's name
  Victim's age
  Victim's gender
  Victim's race
  URL of image of victim
  Date of injury resulting in death (month/day/year)
  Location of injury (address)
  Location of death (city)
  Location of death (state)
  Location of death (zip code)
  Location of death (county)
  Agency responsible for death
  Cause of death
  A brief description of the circumstances surrounding the death
  Official disposition of death (justified or other)
  Criminal Charges?
  Link to news article or photo of official document
  Symptoms of mental illness?
  Unarmed

I meant their methods of analysis for that specific report, not gathering their base dataset.

I did, however, already download their dataset to look through it later, when I have more time.