Development and validation of the peptic ulcer scale under the system of quality of life instruments for chronic diseases based on 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 QLICD-PU

Domain	Number of items	\(\sigma^{2} ({\text{P}})\)	\(\sigma^{2} ({\text{I}})\)	\(\sigma^{2} ({\text{PI}})\)	\(\sigma^{2} (\delta )\)	\(\sigma^{2} (\Delta )\)	\(\sigma^{2} ({\text{X}}_{{{\text{PI}}}} )\)	\({\text{E}}\rho^{2}\)	\(\Phi\)
Physical domain	6	0.517	0.037	0.186	0.186	0.224	0.042	0.735	0.698
	8	0.517	0.028	0.140	0.140	0.168	0.032	0.787	0.755
	9	0.517	0.025	0.124	0.124	0.149	0.029	0.806	0.776
	11	0.517	0.020	0.102	0.102	0.122	0.024	0.836	0.809
Psychological domain	9	0.338	0.010	0.095	0.095	0.105	0.013	0.780	0.763
	11	0.338	0.007	0.069	0.069	0.076	0.010	0.830	0.815
	13	0.338	0.006	0.059	0.059	0.065	0.009	0.852	0.839
	15	0.338	0.005	0.051	0.051	0.056	0.008	0.869	0.858
Social domain	9	0.190	0.010	0.142	0.142	0.152	0.012	0.573	0.556
	11	0.190	0.008	0.116	0.116	0.124	0.010	0.622	0.605
	13	0.190	0.007	0.098	0.098	0.105	0.009	0.660	0.644
	16	0.190	0.006	0.080	0.080	0.085	0.008	0.705	0.690
	17	0.190	0.005	0.075	0.075	0.080	0.007	0.717	0.703
	27	0.190	0.003	0.047	0.047	0.051	0.005	0.801	0.790
	29	0.190	0.003	0.044	0.044	0.047	0.005	0.812	0.801
Specific domain	11	0.143	0.023	0.108	0.108	0.132	0.025	0.568	0.520
	14	0.143	0.018	0.085	0.085	0.103	0.020	0.626	0.580
	17	0.143	0.015	0.070	0.070	0.085	0.016	0.671	0.626
	20	0.143	0.013	0.060	0.060	0.072	0.014	0.705	0.663
	24	0.143	0.011	0.050	0.050	0.060	0.012	0.742	0.703
	34	0.143	0.008	0.035	0.035	0.043	0.009	0.803	0.770
	41	0.143	0.006	0.029	0.029	0.035	0.007	0.831	0.802

Item number for present scale is shown in bold
\(\sigma^{2} (\delta )\) is the variance components of relative error, \(\sigma^{2} (\Delta )\) is the variance components of absolute error, \(\sigma^{2} ({\text{X}}_{{{\text{PI}}}} )\), is the variance components of error when estimating the universe score by using sample mean, \({\text{E}}\rho^{2}\) is the Generalizability coefficient, \(\Phi\) is the index of dependability

ISSN: 1471-230X