This video, by Andrew Sier (UKCEH) and Hilary Geoghegan (University of Reading), explains the importance of evaluation in citizen science projects, explaining how to incorporate it into all stages of a project. It is based on the UKEOF report Understanding Motivations for Citizen Science by Hilary Geoghegan, Alison Dyke, Rachel Pateman and Sarah West.
Watch 'Evaluating a citizen science project'.