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Table 2 Summary of Rasch measurement model on PedsQL™ 3.0 Neuromuscular Module Indonesian Version child self-report

From: Translation and validation of Indonesian version of Pediatric Quality of Life Inventory™ (PedsQL™) Neuromuscular Module

Parameter (with quality criteriaa) The PedsQL™ 3.0 Neuromuscular Module Indonesian Version
Total scale About My Child’s Neuromuscular Disease Subscale Communication Subscale About Our Family Resources Subscale
Model fit: summary of item     
Item mean in logits
(criteria: 0.0 logits)
0.0, SD = 0.37 0.0, SD = 0.42 0.0, SD = 0.22 0.0, SD = 0.42
Item reliability
(criteria: good 0.81–0.90; very good 0.91–0.94; excellent > 0.94)
0.81 0.90 0.00 0.77
Item separation
(criteria: > 3)
2.06 3.02 0.00 1.81
Separate item strata = [(4 × separation index) + 1] / 3
(criteria: fair, 2–3; good, 3–4; very good, 4–5; excellent, > 5)
3.08 \(\approx\) 3 levels 4.36 \(\approx\) 4 levels 0.33 \(\approx\) 0 level 2.75 \(\approx\) 3 level
Item misfit MNSQ range extremes
(criteria: good 0.5–2.0; very good 0.7–1.4; excellent 0.77–1.3)
Infit: 0.53–1.45
Outfit: 0.50–1.73
Infit: 0.74–1.34
Outfit: 0.61–1.58
Infit: 0.65–1.65
Outfit: 0.60–1.60
Infit: 0.81–1,29
Outfit: 0.82–1.13
Point measure correlation
(criteria: 0.4–0.85)
0.31–0.73 0.37–0.75 0.82–0.90 0.71–0.81
Model fit: summary of persons     
Person mean in logits
(criteria: 0.0 logits)
-1.12, SD = 0.92 -1.02, SD = 0.96 -2.34, SD = 1.83 -1.69, SD = 1.65
Person reliability
(criteria: good 0.81–0.90; very good 0.91–0.94; excellent > 0.94)
0.81 0.74 0.36 0.64
Person separation
(criteria: > 2)
2.08 1.68 0.74 1.34
Separate person strata = [(4 × separation index) + 1] / 3
(criteria: fair, 2–3; good, 3–4; very good, 4–5; excellent, > 5)
3.11 \(\approx\) 3 levels 2.57 \(\approx\) 3 levels 1.32 \(\approx\) 1 level 2.12 \(\approx\) 2 levels
Cronbach alpha
(criteria: fair 0.67–0.80; good 0.81–0.90; very good 0.91–0.94; excellent > 0.94)
0.93 0.90 0.85 0.85
Dimensionality     
Raw variance in data explained by measures
(criteria > 40%)
40.9% 45.0% 53.4% 57.5%
Unexplained variance in 1st contrasts of PCA of residuals
(criteria: fair, 10–15%; good, 5–10%; very good, 3–5%; excellent, < 3%)
12.6% 13.7% 36.8% 17.3%
Rating scale analysis     
Average observed
(criteria: increases monotonically across rating scale)
Yes NA NA NA
Outfit MNSQ
(criteria: < 2 logits)
Yes NA NA NA
Adjacent threshold distance
(criteria: 1.4–5 logits)
(i) scale 0–1 was 0 to 0.10 = 0.10 logits; (ii)
scale 1–2 was 0.10 to -0.85 = 0.95 logits; (iii)
scale 2–3 was -0.85 to 0.56 = 1.41 logits; (iv)
scale 3–4 was 0.56 to 0.18 = 0.38 logits
NA NA NA
  1. SD: standard deviation; MNSQ: mean square; NA: not applicable
  2. aRating scale instrument quality criteria (Rasch Measurement Transactions 21, 1095, http://www.rasch.org/rmt/rmt211.pdf)