title: A graphical vector autoregressive modelling approach to the analysis of electronic diary data.
abstract: BACKGROUND
  In recent years, electronic diaries are increasingly used in medical research and practice to investigate patients' processes and fluctuations in symptoms over time. To model dynamic dependence structures and feedback mechanisms between symptom-relevant variables, a multivariate time series method has to be applied.
  
  
  METHODS
  We propose to analyse the temporal interrelationships among the variables by a structural modelling approach based on graphical vector autoregressive (VAR) models. We give a comprehensive description of the underlying concepts and explain how the dependence structure can be recovered from electronic diary data by a search over suitable constrained (graphical) VAR models.
  
  
  RESULTS
  The graphical VAR approach is applied to the electronic diary data of 35 obese patients with and without binge eating disorder (BED). The dynamic relationships for the two subgroups between eating behaviour, depression, anxiety and eating control are visualized in two path diagrams. Results show that the two subgroups of obese patients with and without BED are distinguishable by the temporal patterns which influence their respective eating behaviours.
  
  
  CONCLUSIONS
  The use of the graphical VAR approach for the analysis of electronic diary data leads to a deeper insight into patient's dynamics and dependence structures. An increasing use of this modelling approach could lead to a better understanding of complex psychological and physiological mechanisms in different areas of medical care and research.
authors.affiliation: Department of General Internal Medicine and Psychosomatics, Medical University Hospital Heidelberg, Heidelberg, Germany. beate.wild@med.uni-heidelberg.de
authors.forename: Beate
authors.initials: B
authors.lastname: Wild
authors.forename: Michael
authors.initials: M
authors.lastname: Eichler
authors.forename: Hans-Christoph
authors.initials: HC
authors.lastname: Friederich
authors.forename: Mechthild
authors.initials: M
authors.lastname: Hartmann
authors.forename: Stephan
authors.initials: S
authors.lastname: Zipfel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Herzog
mesh_terms: D000328:Adult; D001007:Anxiety / Q000150:complications; D056912:Binge-Eating Disorder / Q000150:complications / Q000523:psychology*; D003196:Computer Graphics; D034201:Computers, Handheld; D003863:Depression / Q000150:complications; D005260:Female; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D015999:Multivariate Analysis; D009765:Obesity / Q000150:complications / Q000523:psychology*; D012044:Regression Analysis; D055815:Young Adult