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Table 4 Average inter-item correlation and Cronbach’s Alpha scores for study outcome measures at baseline

From: An empirical evaluation of the SF-12, SF-6D, EQ-5D and Michigan Hand Outcome Questionnaire in patients with rheumatoid arthritis of the hand

 

Average Inter- item correlation

Cronbach’s Alphas

Internal Consistency

MHQ

0.45

0.83

Good

EQ-5D (utility)

0.47

0.84

Good

EQ-5D (VAS)

0.48

0.84

Good

SF-12 (PCS)

0.46

0.84

Good

SF-12 (MCS)

0.52

0.87

Good

SF-6D

0.44

0.83

Good

  1. Internal consistency is considered unacceptable for α <0.5, poor for 0.6 > α ≥ 0.5, questionable for 0.7 > α ≥ 0.6, acceptable for 0.8 > α ≥ 0.7, good for 0.9 > α ≥ 0.8 and excellent for α ≥ 0.9 [32, 34]