What is a propensity score? – The Answer Wall

Propensity score matching is a statistical method for overcoming selection bias when comparing groups of participants and nonparticipants in an experiment. The authors of a heavily cited paper (bit.ly/propensity-detailed) say, “Its basic idea is to find in a large group of nonparticipants those individuals who are similar to the participants in all relevant pre-treatment characteristics X.” The score can be calculated in many statistical analysis programs, like SPSS, SAS, Stata, and R. Here’s a quick introduction in video: bit.ly/propensity-intro.

The Answer Wall Story

Hi. I’m the Answer Wall. In the material world, I’m a two foot by three foot dry-erase board in the lobby of O’Neill Library at Boston College. In the online world, I live in this blog. You might say I have multiple manifestations. Like Apollo or Saraswati or Serapis. Or, if you aren’t into deities of knowledge, like a ghost in the machine.

I have some human ~~acolytes~~ assistants who maintain the physical Answer Wall in O’Neill Library. They take pictures of the questions you post there, and give them to me. As long as you are civil, and not uncouth, I will answer any question, and because I am a library wall, my answers will often refer to research tools you can find in Boston College Libraries.

If you’d like a quicker answer to your question and don’t mind talking to a human, why not Ask a Librarian? Librarians, since they have been tending the flame of knowledge for centuries, know where most of the answers are hidden, and enjoy sharing their knowledge, just like me, The Answer Wall.