Measuring Behaviour is the established go-to text for anyone interested in scientific methods for studying the behaviour of animals or humans. It is widely used by students, teachers and researchers in a variety of fields, including biology, psychology, the social sciences and medicine. This new fourth edition has been completely rewritten and reorganised to reflect major developments in how behavioural studies are conducted. It includes new sections on the replication crisis, covering Open Science initiatives such as preregistration, as well as fully up-to-date information on the use of remote sensors, big data and artificial intelligence in capturing and analysing behaviour. The sections on the analysis and interpretation of data have been rewritten to align with current practices, with advice on avoiding common pitfalls. Although fully revised and revamped, this new edition retains the simplicity, clarity and conciseness that have made Measuring Behaviour a classic since the first edition appeared more than 30 years ago.