OnDatReddit

I can tie a knot with my tongue, I love puns, I have a habit of chewing on pen caps, and I have an intense hate for P.T Cruisers. What's that say about me?

Have they ever offered to massage you?

A lot of Psychologist claim it was not a valid test, because participants were not chosen at random, they were selected. So there was selection bias. Zimbardo used advertisement promising a "psychology experiment with prison life". Therefore attracting participants that are more prone to be more violent than the general population. Do you think results were skewed or bias?