title: The development and validation of a Real Time Location System to reliably monitor everyday activities in natural contexts.
abstract: BACKGROUND
  The accurate measurement of behaviour is vitally important to many disciplines and practitioners of various kinds. While different methods have been used (such as observation, diaries, questionnaire), none are able to accurately monitor behaviour over the long term in the natural context of people's own lives. The aim of this work was therefore to develop and test a reliable system for unobtrusively monitoring various behaviours of multiple individuals within the same household over a period of several months.
  
  
  METHODS
  A commercial Real Time Location System was adapted to meet these requirements and subsequently validated in three households by monitoring various bathroom behaviours.
  
  
  RESULTS
  The results indicate that the system is robust, can monitor behaviours over the long-term in different households and can reliably distinguish between individuals. Precision rates were high and consistent. Recall rates were less consistent across households and behaviours, although recall rates improved considerably with practice at set-up of the system. The achieved precision and recall rates were comparable to the rates observed in more controlled environments using more valid methods of ground truthing.
  
  
  CONCLUSIONS
  These initial findings indicate that the system is a valuable, flexible and robust system for monitoring behaviour in its natural environment that would allow new research questions to be addressed.
authors.affiliation: Environmental Health Group, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Gaby
authors.initials: G
authors.lastname: Judah
authors.affiliation: Environmental Health Group, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Jessie
authors.identifier: http://orcid.org/0000-0003-3757-2240
authors.initials: J
authors.lastname: de Witt Huberts
authors.affiliation: Center for advanced Studies in Adaptive Systems (CASAS), Washington State University, Pullman, Washington, United States of America.
authors.forename: Allan
authors.initials: A
authors.lastname: Drassal
authors.affiliation: Environmental Health Group, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Aunger
mesh_terms: D000203:Activities of Daily Living; D003199:Computer Systems; D005191:Family Characteristics; D006801:Humans; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012371:Robotics / Q000295:instrumentation / Q000379:methods