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Table 2 Internal consistency and reliability

From: Measuring respiratory symptoms of COPD: performance of the EXACT- Respiratory Symptoms Tool (E-RS) in three clinical trials

Reliability parameter Mpex AZ 1 AZ 2
  (N = 235) (N = 749) (N = 597)
Internal consistency* Daily Weekly Daily Weekly Daily Weekly
 RS-Total Score 0.88 0.90 0.92 0.94 0.92 0.95
 RS-Breathlessness 0.89 0.93 0.90 0.94 0.90 0.94
 RS-Cough and Sputum 0.40 0.52 0.68 0.73 0.71 0.78
 RS-Chest Symptoms 0.92 0.96 0.89 0.94 0.87 0.93
Reproducibility of daily scores§ Day 1-2 Day -7 to -1   Day -7 to -1   Day -7 to -1
(N = 170) (N = 235)   (N = 715)   (N = 597)
 RS-Total Score 0.91 0.71 N/A 0.74 N/A 0.74
 RS-Breathlessness 0.87 0.73 N/A 0.71 N/A 0.74
 RS-Cough and Sputum 0.84 0.58 N/A 0.71 N/A 0.69
 RS-Chest Symptoms 0.89 0.69 N/A 0.71 N/A 0.69
  1. *Cronbach's alpha.
  2. Day -1.
  3. Day -7 to Day -1.
  4. §ICC, random-effects model, Day -7 to Day -1.
  5. Abbreviations: AZ AstraZeneca, ICC intraclass correlation coefficient, N/A not available (no global assessment of day-to-day stability).