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now an osteopath: certainly an unusual combination. You can read about her on her Wikipedia page: https://en.wikipedia.org/wiki/Rosi_Sexton. The video is long and wide-ranging, so I’ll give some bookmarks, in case you don’t want to watch it all. (And please excuse my garish London marathon track suit.) Rosi recently started to take piano lessons again, after a 20 year break. She plays Chopin in the introduction, and Prokofiev and Schubert at 17:37 - 20:08. They are astonishingly good, given the time that’s elapsed since she last played seriously. We started corresponding in 2011, about questions concerning evidence and alternative medicine as well as sports. Later we talked about statistics too: her help is acknowledged in my 2017 paper: http://rsos.royalsocietypublishing.org/content/4/12/171085. And discussions with her gave rise to the slide at 26:00 in https://www.youtube.com/watch?v=iFaIpe9rFR0. Rosi’s accomplishments in MMA have been very well-documented and my aim was to concentrate on her other achievements. Nonetheless we inevitably had to explore the reasons why a first class mathematician chose to spend 14 years of her life in such a hard sport. I’m all for people taking risks if they want to. I have more sympathy for her choice than many of my friends, having spent time doing boxing, rugby, flying, sailing, long distance running, and mountain walking. I know how they can provide a real relief from the pressures of work: [see http://www.dcscience.net/DCsports/index.html ] The interview starts by discussing when she started music (piano, age 6) and how she became interested in maths. In her teens, she was doing some quite advanced maths: she relates (at 1:22:50) how she took on holiday some of Raymond Smullyan’s books on mathematical logic at the age of 15 or 16. She was also playing the piano and the cello in the Reading Youth Orchestra, and became an Associate of the London College of music at 17. And at 14 she started Taekwondo, which she found helpful in dealing with teenage demons. She was so good at maths that she was accepted at Trinity College, Cambridge where she graduated with 1st class hons. And then went on to a PhD, at Manchester. It was during her PhD that she became interested in MMA. We talk at 23:50 about why she abandoned maths (there’s a glimpse of some of her maths at 24:31), and devoted herself to MMA until she retired from that in 2014. In the meantime she took her fifth degree, in osteopathy, in 2010. She talks about some of her teenage demons at 28:00 (from a 2010 documentary). Many of my sceptical friends regard all osteopaths as quacks. Some certainly are. I asked Rosi about this at 38:40 and her responses can’t be faulted. She agrees that it’s rarely possible to know whether the treatments she uses are effective or whether the patient would have improved anyway. She understands regression to the mean. We discussed the problem of responders and non-responders. She appreciates that it’s generally not possible to tell whether or not they exist (for more on this, see Stephen Senn’s work, e.g. https://www.youtube.com/watch?v=_wQE9-S250o. Even the best RCT tells us only about the average response. We talk about the problems of doping and of trans competitors in sports at 49:00, and about the perception of contact sports at 59:30. Personally I have no problem with people competing in MMA, boxing or rugby, if that’s what they want to do. Combat sports are the civilised alternative to war. It isn’t the competitors that I worry about, it’s the fans. At 1:14:28 we discussed how little is known about the long-term dangers of contact sports. The possible dangers of concussion led to a discussion of Russell’s paradox at 1:20:40 I asked why she’s reluctant to criticise publicly things like acupuncture or “craniosacral therapy” (at 1:25:00). I found her answers quite convincing. At 1:43:50, there’s a clip taken from a 2010 BBC documentary of Rosi’s father speaking about his daughter’s accomplishments, her perfectionism and her search for happiness. Lastly, at 1:45:27, there’s a section headed “A happy new beginning”. It documents Rosi’s 40th birthday treat, when she with her new partner, Stephen Caudwell, climbed the highest climbing wall in the world, the Luzzone dam -see more at https://rosisexton.wordpress.com/2017/08/02/its-a-long-way-down/. After they walked down at the end of the climb, they got engaged. I wish them both a very happy future.