title: A Visualization Tool to Analyse Usage of Web-Based Interventions: The Example of Positive Online Weight Reduction (POWeR).
abstract: BACKGROUND
  Attrition is a significant problem in Web-based interventions. Consequently, this research aims to identify the relation between Web usage and benefit from such interventions. A visualization tool has been developed that enables researchers to more easily examine large datasets on intervention usage that can be difficult to make sense of using traditional descriptive or statistical techniques alone.
  
  
  OBJECTIVE
  This paper demonstrates how the visualization tool was used to explore patterns in participants' use of a Web-based weight management intervention, termed "positive online weight reduction (POWeR)." We also demonstrate how the visualization tool can be used to perform subsequent statistical analyses of the association between usage patterns, participant characteristics, and intervention outcome.
  
  
  METHODS
  The visualization tool was used to analyze data from 132 participants who had accessed at least one session of the POWeR intervention.
  
  
  RESULTS
  There was a drop in usage of optional sessions after participants had accessed the initial, core POWeR sessions, but many users nevertheless continued to complete goal and weight reviews. The POWeR tools relating to the food diary and steps diary were reused most often. Differences in participant characteristics and usage of other intervention components were identified between participants who did and did not choose to access optional POWeR sessions (in addition to the initial core sessions) or reuse the food and steps diaries. Reuse of the steps diary and the getting support tools was associated with greater weight loss.
  
  
  CONCLUSIONS
  The visualization tool provided a quick and efficient method for exploring patterns of Web usage, which enabled further analyses of whether different usage patterns were associated with participant characteristics or differences in intervention outcome. Further usage of visualization techniques is recommended to (1) make sense of large datasets more quickly and efficiently; (2) determine the likely active ingredients in Web-based interventions, and thereby enhance the benefit they may provide; and (3) guide in designing (or redesigning) of future interventions to promote greater use and engagement by enabling users to easily access valued intervention content/tools.
  
  
  BACKGROUND
  International Standard Randomized Controlled Trial Number (ISRCTN): 31685626; http://www.isrctn.com/ISRCTN31685626 (Archived by WebCite at http://www.webcitation.org/6YXYIw9vc).
authors.affiliation: Department of Psychology, Faculty of Science and Technology, Bournemouth University, Poole, United Kingdom. eardenclose@bournemouth.ac.uk.
authors.forename: Emily Julia
authors.identifier: http://orcid.org/0000-0002-5954-2598
authors.initials: EJ
authors.lastname: Arden-Close
authors.forename: Emily
authors.identifier: http://orcid.org/0000-0003-1974-4061
authors.initials: E
authors.lastname: Smith
authors.forename: Katherine
authors.identifier: http://orcid.org/0000-0001-5513-7571
authors.initials: K
authors.lastname: Bradbury
authors.forename: Leanne
authors.identifier: http://orcid.org/0000-0002-9961-551X
authors.initials: L
authors.lastname: Morrison
authors.forename: Laura
authors.identifier: http://orcid.org/0000-0003-0122-6610
authors.initials: L
authors.lastname: Dennison
authors.forename: Danius
authors.identifier: http://orcid.org/0000-0001-5430-3267
authors.initials: D
authors.lastname: Michaelides
authors.forename: Lucy
authors.identifier: http://orcid.org/0000-0002-3853-883X
authors.initials: L
authors.lastname: Yardley
keywords: Web-based interventions; data visualisations; usage