racial disparities in police killings using bayes theorem

The Washington Post has been tracking police killings across the nation. Last week, Peter Aldhous published an analysis of these data.1 He figured that blacks suspects were 37.8% of all unarmed suspects killed by police. White suspects made up a nearly similar percentage of unarmed suspects killed by police, despite the fact that there are almost five times as many whites in the United States as blacks.

This does not provide the best evidence to adjudicate racial disparities in police violence, however. Aldous writes:

Video of McDonald’s last moments, shot 16 times by a white officer, made a stark contrast with images of a handcuffed Robert Lewis Dear, the white suspect in the shooting at a Planned Parenthood clinic in Colorado Springs — as activists were quick to point out.

Rather than figure out the probability that an unarmed suspect was black, it would be important to know the probability that a black suspect shotkilled by police was unarmed. We care less whether an unarmed victim was black as we do whether a black victim was unarmed. That would be more in line with, though not exactly equivalent to, what Aldhous wrote.2

Below, I try to explain how we can use rules of probability to explain this problem to an introductory statistics class. Continue reading “racial disparities in police killings using bayes theorem”

affirmative action can’t make itself unnecessary

I spent this morning reading the oral arguments in the second round of Fisher v. Texas, the most recent Supreme Court case on affirmative action in admissions. It’s fascinating to see how the debate plays out, and how it picks up right where the debate in Grutter ended in 2003, with nothing fundamentally resolved.* One issue keeps frustrating me that I haven’t seen discussed in the secondary coverage. Several times the conversation turns to the claim made in the Grutter decision that affirmative action might only be needed for another 25 years. We’re halfway through that, the Justices note, and Scalia asks bluntly: “do you think all of this won’t be necessary in another 13 years?” But here’s the thing: affirmative action can’t make itself unnecessary.

Continue reading “affirmative action can’t make itself unnecessary”

cost-cutting in higher ed

In the Washington Post earlier this week, Steve Pearlstein published a piece promoting four things universities should do to cut costs:

  1. Cap administrative costs
  2. Operate year round, five days a week
  3. More teaching, less (mediocre) research
  4. Cheaper, better general education

The next day, Daniel Drezner responded with four things columnists should do before writing about universities.

  1. Define what you mean by “universities.”
  2. Don’t exaggerate the problems that actually exist.
  3. Don’t rely on outdated data.
  4. Be honest that you’re using higher ed reform as an implicit industrial policy.

Continue reading “cost-cutting in higher ed”

clashing norms of proper deference

I posted this on FB. “How to be deferential but not excessively deferential: If you have a scheduled appointment with your professor and you can tell she is talking to someone else, knock or stick your head in so you are sure she knows you are there, then back up apologetically and say “I’ll be happy to wait.” Quietly waiting without letting her know you are there is a problem because she may prefer to get rid of the person in her office and stick to her schedule rather than run late with you, and she should be the one who gets to decide this.”

In my office configuration I cannot see the hall from my desk and I have OFTEN been chatting aimlessly with someone, telling them “I’m expecting a student soon” and then even “I wonder where my 3pm appointment is, did he forget?” while, unbeknownst to me, the student is sitting or standing quietly and patiently outside the door, never announcing their presence. This drives me crazy, as it seems going way overboard in the deference direction when you have an actual scheduled appointment with someone not to announce that you have arrived for it. Thus, when given the opportunity, I instruct students (as above) about how one can simultaneously exhibit politeness and deference while also honoring schedules. However,  former students (who are now professors themselves) confirm that their own sense of deference would lead them NEVER to interrupt a conversation a professor was involved with.

Is there any hope for this culture clash? I obviously need to return to the sign on my door that says “please tell me if you are waiting for me.” But even when I used to have that sign on the door, I’d have students who either would not notice the sign or not think it applied to them.

 

 

what does ‘why’ mean?

A couple of weeks ago I got in a friendly back-and-forth on Twitter with my friend and colleague Daniel Kreiss. Daniel was annoyed by this article, which purports to reveal why Mitt Romney chose Paul Ryan to be his running mate by deploying median-voter theory. Daniel’s frustration was this:

 

Here’s the record of our conversation. More thoughts below the break.

Continue reading “what does ‘why’ mean?”