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Table 2 Convergent and discriminant validity results for PA questions

From: Using a single question to assess physical activity in older adults: a reliability and validity study

  Absolute Questiona Relative Questionb
Validation Measure r (95% CI)c r (95% CI)c
Convergent validity   
   Total score on Berg Balance Scale (n = 158) 0.31 (0.17, 0.45) 0.48 (0.35, 0.59)
   Unsteady gait (n = 152) 0.24 (0.12, 0.40) 0.40 (0.26, 0.56)
   Gait-path (n = 93) 0.32 (0.17, 0.53) 0.57 (0.38, 0.78)
   Gait-trunk (n = 94) 0.29 (0.15, 0.50) 0.42 (0.25, 0.63)
   Gait-abnormality (n = 93) 0.26 (0.00, 0.47) 0.36 (0.20, 0.57)
   Lower extremity weakness (n = 92) 0.21 (0.00, 0.43) 0.37 (0.21, 0.58)
   Postural stability (n = 94) 0.17 (0.00, 0.38) 0.33 (0.17, 0.54)
   Walking ability (n = 158) 0.33 (0.19, 0.49) 0.42 (0.28, 0.58)
   Housework difficulty (n = 158) 0.28 (0.16, 0.45) 0.34 (0.20, 0.50)
   Limits activity-fear of falling (n = 155) 0.10 (0.00, 0.26) 0.28 (0.15, 0.44)
   Pain affects mobility (n = 90) 0.28 (0.00, 0.50) 0.34 (0.18, 0.55)
Discriminant validity   
   Home hazards (n = 152) 0.04 (0.00, 0.19) 0.02 (0.00, 0.12)
   Vision (n = 157) 0.05 (0.00, 0.21) 0.07 (0.00, 0.23)
   Skin problems (n = 157) 0.13 (0.00, 0.29) 0.15 (0.00, 0.32)
   Hearing deficit (n = 94) 0.29 (0.15, 0.50) 0.24 (0.00, 0.44)
  1. a Response categories: i) seldom active; ii) moderately active; or iii) vigorously active.
  2. b Response categories: i) less active; ii) about as active; or iii) more active.
  3. c Specific type of correlation coefficient (r): Spearman's rho (total score on Berg Balance Scale) and Cramer's V (all other validation measures)
  4. Validation measures and PA questions were ordered so that higher scores indicated better functioning or higher PA levels.
  5. Abbreviations: CI = Confidence Interval; PA = Physical Activity.
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BMC Medical Research Methodology

ISSN: 1471-2288

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