Development and calibration of a novel social relationship item bank to measure health-related quality of life (HRQoL) in Singapore

Table 2 Criteria for evaluating adequacy of meeting IRT assumptions and results

Unidimensionality
Approach	Criterion	Reference	Results	Criterion met?
EFA	Percentage of variance accounted for by first factor > 20%	PROMIS [16]	18.1%	No
EFA	Ratio of first to second eigenvalues > 4.0	PROMIS [16]	8.01	Yes
CFA	CFI > 0.95	PROMIS [16]	0.923	No
	TLI > 0.95	PROMIS [16]	0.917	No
	RMSEA < 0.06	PROMIS [16]	0.098	No
	SRMR < 0.08	PROMIS [16]	0.081	No
Bifactor analyses	ARPB < 10%	Muthén, Kaplan, and Hollis (1987) [33]	3.6%^§	Yes
	General ECV > 0.70	Reise, Bonifay and Haviland (2013) [17]	0.805^ǂ	Yes
	OmegaH > 0.80	Reise, Bonifay and Haviland (2013) [17]	0.980^¥	Yes
	General ECV > 0.60 and OmegaH> 0.70	Reise, Schienes, Widaman and Haviland (2013) [15]		Yes
Local Independence
Residual correlation matrix	Average absolute residual correlations < 0.10	PROMIS[16]	0.067	Yes
	Percentage of residual correlations above 0.20	Artmann et al. 2010 [18]	1.84%	No threshold given
	Percentage of residual correlations above 0.20	Artmann et al. 2010 [18]	(8 of 435)	No threshold given

Abbreviations: Item response theory (IRT), comparative fit index (CFI), Tucker-Lewis Index (TLI), root mean square error of approximation (RMSEA), standardized root mean residual (SRMR), explained common variance (ECV), item explained common variance (IECV), omega hierachical (omegaH), explanatory factor analysis (EFA), confirmatory factor analysis (CFA)
^§Maximum ARPB among three exploratory bifactor models with 2,3 and 4 specific factors. See Table 3
^ǂMinimum general factor ECV attained among three exploratory bifactor models with 2, 3 and 4 specific factors. See Table 3
^¥ Minimum OmegaH attained among three exploratory bifactor models. See Table 3

ISSN: 1477-7525