Much epidemiological and health services research relies on surveys and Jousilahti et al’s paper¹ is a timely reminder to us about the biases caused by participants’ non-response. Although we all know that non-response is a socially patterned phenomenon, this knowledge is so familiar that it is easy to become complacent—how many of us have ticked the mental boxes of “>70%” and “information about response biases” as markers of a good quality survey when reading or reviewing a paper? Jousilahti et al’s paper is valuable in that it provides data …