title: Score equivalence of electronic and paper versions of the Social Difficulties Inventory (SDI-21): a randomised crossover trial in cancer patients.
abstract: OBJECTIVE
  The Social Difficulties Inventory (SDI-21) assesses everyday problems experienced by cancer patients, including difficulties with self-care, work and relationships. Early development and psychometric evaluation studies have validated the SDI-21 for computer administration. However, several recent studies have administered the SDI-21 on paper. We sought to test the score equivalence of electronic and paper versions of the SDI-21.
  
  
  METHODS
  A randomised two-arm crossover trial in a sample of cancer patients with varied diagnoses. Patients completed electronic (via the internet) and paper versions of the SDI-21, with half randomly assigned to complete the electronic version first (n = 51) and half the paper version first (n = 60). Patients were asked to complete both versions at home, within 2 weeks. Analyses were performed for the SDI-21 summary score and three subscales.
  
  
  RESULTS
  Score distributions and internal reliabilities for the paper and electronic versions were highly similar. There were no significant differences between mean summary or subscale scores for the two administration modes. All mean score differences (all <0.25 of a scale point) were well below the SDI-21's established minimally important differences, and all 95 % confidence intervals were narrow and included zero. Intraclass correlations between paper and electronic scores were uniformly high and significant (all ≥0.85) and above the standard acceptable level of reliability.
  
  
  CONCLUSIONS
  Paper and electronic versions of the SDI-21 can be considered equivalent and used interchangeably. This is important because, despite the growth of electronic formats, paper versions are currently still necessary to ensure inclusive use of the SDI-21 with representative samples.
authors.affiliation: Psychosocial Oncology and Clinical Practice Research Group, University of Leeds, Level 3, Bexley Wing, St James's Institute of Oncology, Leeds, LS9 7TF, UK. l.j.ashley@leeds.ac.uk
authors.forename: Laura
authors.initials: L
authors.lastname: Ashley
authors.forename: Ada
authors.initials: A
authors.lastname: Keding
authors.forename: Julia
authors.initials: J
authors.lastname: Brown
authors.forename: Galina
authors.initials: G
authors.lastname: Velikova
authors.forename: Penny
authors.initials: P
authors.lastname: Wright
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000523:psychology*; D010209:Paper; D010555:Personality Inventory; D011594:Psychometrics / Q000706:statistics & numerical data; D011788:Quality of Life; D015203:Reproducibility of Results; D012648:Self Care; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires