How can we best used evidence in medicine, from hospitals and GP practices to the sphere of public health and policymaking? Is all current medical practice backed by sufficient evidence? How should doctors approach uncertainty? How can we scrutinise claims made in the clinic, papers and the media alike? To throw some light on some of these questions and more is Dr Margaret McCartney. A strong advocate for evidence-based medicine, Dr McCartney works as a GP in Glasgow and currently serves on the council of the Royal College of GPs. She has made regular contributions to the Guardian, the British Medical Journal and BBC Radio 4s inside health where she has explored topics ranging from screening, to conflict of interest in medicine and healthcare politics.