Development and validation of the coronary heart disease scale under the system of quality of life instruments for chronic diseases QLICD-CHD: combinations of classical test theory and Generalizability theory

Table 5 G-coefficients and Ф-coefficients for different numbers of items for p × I design in D-study for four domains of quality of life instrument QLICP-CHD

Domain	Number of items	σ²(P)	σ²(I)	σ²(PI)	σ²(δ)	σ²(∆)	σ²(×_PI)	σ²(Eρ²)	Φ
Physical domain	6	0.51	0.01	0.20	0.20	0.21	0.02	0.72	0.70
	8	0.51	0.01	0.15	0.15	0.16	0.02	0.77	0.76
	10	0.51	0.01	0.12	0.12	0.13	0.01	0.81	0.80
	12	0.51	0.01	0.10	0.10	0.11	0.01	0.84	0.83
	14	0.51	0.01	0.09	0.09	0.09	0.01	0.86	0.85
Psychological domain	9	0.59	0.02	0.07	0.07	0.09	0.02	0.89	0.87
	10	0.59	0.02	0.07	0.07	0.08	0.02	0.90	0.88
	11	0.59	0.01	0.06	0.06	0.07	0.02	0.91	0.89
	12	0.59	0.01	0.06	0.06	0.07	0.02	0.92	0.90
	13	0.59	0.01	0.05	0.05	0.06	0.02	0.92	0.91
Social domain	9	0.21	0.03	0.14	0.14	0.17	0.03	0.59	0.55
	11	0.21	0.02	0.12	0.12	0.14	0.03	0.64	0.60
	13	0.21	0.02	0.10	0.10	0.12	0.02	0.67	0.63
	15	0.21	0.02	0.09	0.09	0.10	0.02	0.71	0.67
	17	0.21	0.02	0.08	0.08	0.09	0.02	0.73	0.70
Specific domain	14	0.26	0.01	0.08	0.08	0.09	0.01	0.77	0.75
	16	0.26	0.01	0.07	0.07	0.08	0.01	0.80	0.77
	18	0.26	0.01	0.06	0.06	0.07	0.01	0.81	0.79
	20	0.26	0.01	0.05	0.05	0.06	0.01	0.83	0.81
	22	0.26	0.01	0.05	0.05	0.06	0.01	0.84	0.82

σ²(δ) is the variance components of relative error.
σ²(∆) is the variance components of absolute error.
σ²(×_PI) is the variance components of error when estimating the universe score by using sample mean.
σ²(Eρ²) is the Generalizability coefficient.
Φ is the index of dependability.

ISSN: 1477-7525