I did *not* expect an effect this large, I'm really surprised. 40% of ppl with abusive childhoods are into bdsm, whereas 25% without abusive childhoods are into bdsm. !!!!!!!
I read the thread on selection bias and agree with your points but this man's critique seems to be about the fact that 80% of respondents were not abused and therefore conclusions about abuse:BDSM came from a sample size of 434.
(The theory is interesting)