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Table 4 Rasch item statistics for Singapore ASQoL

From: Adaptation of Chinese and English versions of the Ankylosing Spondylitis quality of life (ASQoL) scale for use in Singapore

Item Item Calibration in logits (SE) INFIT (MNSQ) OUTFIT (MNSQ) DIF Probability by Mantel-Haenszel statistics (p)
Gender Agea Languageb
#1 −0.64 (0.20) 1.14 1.25 0.4381 0.0074 0.7937
#2 0.48 (0.23) 0.99 0.89 0.0005 0.9200 0.5870
#3 1.56 (0.30) 1.08 0.93 0.5964 0.0037 0.6836
#4 0.63 (0.24) 0.80 0.69 0.9713 0.2586 0.9458
#5 1.09 (0.26) 0.87 0.78 0.7520 0.0476 0.9763
#6 −0.51 (0.20) 1.07 1.14 0.6056 0.8955 0.1197
#7 −0.58 (0.20) 0.95 0.87 0.0476 0.2484 0.0850
#8 −0.85 (0.20) 0.78 0.68 0.5995 0.9560 0.8635
#9 1.02 (0.26) 0.90 0.72 0.5301 0.5218 0.1634
#10 0.32 (0.23) 0.94 1.01 0.0631 0.9597 0.1467
#11 1.94 (0.33) 1.09 0.95 0.5933 0.6896 0.3634
#12 −1.61 (0.20) 0.86 0.74 0.1651 0.0992 0.0293
#13 −0.55 (0.20) 0.89 0.97 0.4904 0.1512 0.6042
#14 −1.69 (0.20) 1.45 1.66 0.7045 0.6147 0.0397
#15 −0.51 (0.20) 0.92 0.82 0.6857 0.2089 0.0286
#16 2.44 (0.38) 1.00 1.29 0.4703 0.0555 0.1191
#17 −1.31 (0.20) 1.13 1.12 0.4670 0.9162 0.9222
#18 −1.23 (0.20) 1.04 0.95 0.5116 0.2195 0.7969
  1. Bold italics = MNSQ values outside range of 0.7 to 1.3. Italics = Bonferroni adjusted p < 0.0027 (denote concern of DIF)
  2. INFIT information-weighted fit statistics, OUTFIT outlier-sensitive statistics, MNSQ mean square, DIF differential item functioning
  3. aAge < 50 years vs. ≥50 years; bChinese vs. English