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Table 3 Results from tests of scaling properties of Malaysian translated version of the St George’s Respiratory COPD specific Questionnaire

From: Validation and clinical interpretation of the St George’s respiratory questionnaire for COPD (SGRQ-C) after adaptation to Malaysian language and culture, in patients with COPD

 SymptomActivityImpactSGRQ-CM
Items n7132040
Theoretical Range0–1000–1000–1000–100
Observed range8.88–10022.39–1009.23–90.6117.59–92.32
At ceiling % (n) a2.1 (3)4.3 (6)00
At Floor % b0000
Item Convergent Validity c0.44–0.790.14–0.720.13–0.68__
Scaling Success % d87.584.680__
Cronbach’s α Coefficient0.740.700.710.87
Test-Retest reliability e
Mean Difference f−3.02766−.78737−1.37505−1.44755
ICC0.890.850.900.88
  1. a Best possible score; b Worst possible score; c range of correlation between item and their hypothesized scale; d Percentage of items correlated higher with the hypothesized subscale than other subscale; e test retest was performed on 48 patients; f Mean difference in baseline and 2 weeks SGRQ-CM scores; n number, ICC Intraclass correlation coefficient, SGRQ-CM St George’s Respiratory COPD specific Questionnaire Malaysian version