title: Ambulatory and diary methods can facilitate the measurement of patient-reported outcomes.
abstract: OBJECTIVE
  Ambulatory and diary methods of self-reported symptoms and well-being have received increasing interest in recent years. These methods are a valuable addition to traditional strategies for the assessment of patient-reported outcomes (PROs) in that they capture patients' recent symptom experiences repeatedly in their natural environments. In this article, we review ways that incorporating diary methods into PRO measurement can facilitate research on quality of life.
  
  
  METHODS
  Several diary methods are currently available, and they include "real-time" (Ecological Momentary Assessment) and "near-real-time" (end-of-day assessments, Day Reconstruction Method) formats. We identify the key benefits of these methods for PRO research.
  
  
  RESULTS
  (1) In validity testing, diary assessments can serve as a standard for evaluating the ecological validity and for identifying recall biases of PRO instruments with longer-term recall formats. (2) In research and clinical settings, diaries have the ability to closely capture variations and dynamic changes in quality of life that are difficult or not possible to obtain from traditional PRO assessments. (3) In test construction, repeated diary assessments can expand understanding of the measurement characteristics (e.g., reliability, dimensionality) of PROs in that parameters for differences between people can be compared with those for variation within people.
  
  
  CONCLUSIONS
  Diary assessment strategies can enrich the repertoire of PRO assessment tools and enhance the measurement of patients' quality of life.
authors.affiliation: Dornsife Center for Self-Report Science, Center for Economic and Social Research, University of Southern California, 635 Downey Way, Los Angeles, CA, 90089-3332, USA. schneids@usc.edu.
authors.forename: Stefan
authors.identifier: http://orcid.org/0000-0002-4562-0524
authors.initials: S
authors.lastname: Schneider
authors.affiliation: Dornsife Center for Self-Report Science, Center for Economic and Social Research, University of Southern California, 635 Downey Way, Los Angeles, CA, 90089-3332, USA.
authors.forename: Arthur A
authors.initials: AA
authors.lastname: Stone
mesh_terms: D006305:Health Status Indicators; D006801:Humans; D008499:Medical Records; D011939:Mental Recall; D063868:Patient Outcome Assessment; D011788:Quality of Life; D015203:Reproducibility of Results; D057566:Self Report
keywords: Ambulatory measurement; Day Reconstruction Method; Diaries; Ecological Momentary Assessment; Patient-reported outcomes; Recall