Plan, do, study, act cycles, or PDSA cycles, are the basis of many quality improvement projects, they're a model to trial changes and feed the lessons from each test into the next.

Why are they a popular method, and how do you get the best out of them? And what on earth happens when they explode?

Harriet Vickers asks Julie Reed, National Institute for Healthcare Research CLAHRC (Collaboration for Leadership in Applied Health Research and Care) for north west London.

Read all of Julie's paper (for free): http://qualitysafety.bmj.com/content/25/3/147