I was moved by the obituary of Nick Hitchon (Other lives, 27 August), whose life we all had the privilege of tracking through the wonderful Up series. It was brilliant of the late Michael Apted and his colleagues to make these documentary films, but it was very brave and generous-spirited of the people such as Nick who allowed their privacy to be invaded, to be used as case studies. As a university teacher, I encouraged my students to watch the programmes and used them in teaching. They illustrated so clearly the significance of early experience and access to opportunity – more vividly than textbooks and larger, more scientifically rigorous but less revealing surveys and analyses. There were a few surprises, but not many, as these individuals grew up and met the challenges that faced them. They became like relatives we heard about periodically, and we cared about them. I’m sure participating in the study had an impact on them, and that would be another study in itself. But I would like to thank all of them. They did something very valuable, and provided real insights for viewers and for social scientists. Prof Kate Purcell Coventry