This comment is probably going to be a bit rough, but here's just a few things I immediately picked up on:
Not all of the people listed are mass shooters.
You included suicides and a chimpanzee, but failed to mention Colin Ferguson, who killed 6 and wounded 19 in 1993. If you're doing mass shootings, he should probably be up there.
Your population classification system is a bit unusual, as "aberrant adult" suggests that there isn't something aberrant about the other population groups. NEETs like Elliot Rodger and Ted Kaczsynski best fit that description, while others appeared functional and employed, like Omar Mateen and Randy Stair.
Omar Mateen was ethnically an Afghan, and more precisely a Pashtun. In general, your race/ethnicity category is pretty confusing, since you include nationality for some, and not for others. Tomohiro Kato was Japanese for example, and Seung-Hui Cho was born in the Republic of Korea, but you classified him as "Asian descent". You also classify Marc Lepine as "caucasian/african descent" where he was Canadian/Algerian. Another example is Kimveer Gill, who was a subcontinental of Punjabi heritage. Unless you're British, classifying him as Asian is confusing for the reader. There's also Dimitrious Pagourtzis, who was of Greek heritage, but Greeks are Caucasian. It seems unnecessary to add that he was Caucasian of Greek descent, as you haven't done that with the majority.
You also say that Timothy McVeigh had a "mixed" attack type, despite targeting a particular population, while saying that Brenda Spencer was "mixed" despite targeting kids at complete random. Even she couldn't give a clear reason why she picked up a gun and shot at students and school staff. If you consider Anton Peterson to have targeted a specific population, then it stands to reason that Timothy McVeigh did, despite his imprecise weapon of choice.
Subject: Re: Spreadsheet And Langman's Typology 
Mon Dec 10, 2018 3:11 am