Table 5.

Estimation of factor loadings and MIRT parameters of items using the pooled panel data

	Pearson’s correlation	Factor loadings		MIRT parameters
		λ 1 (SE)	λ 2 (SE)	a 1 (SE)	a 2 (SE)	d 1 (SE)	d 2 (SE)	d 3 (SE)
1. Dry and hard stool	0.76*	0.76 (0.07)*	0.70 (0.07)*	2.67 (0.31)*	1.54 (0.23)*	3.07 (0.30)*	−1.56 (0.20)*	−5.96 (0.45)*
2. Prolonged interval of spontaneous defecation	0.73*	0.70 (0.07)*	0.48 (0.09)*	2.20 (0.24)*	1.50 (0.20)*	1.70 (0.20)*	−3.09 (0.23)*	−6.36 (0.46)*
3. Sensation of incomplete evacuation	0.65*	0.70 (0.06)*	0.32 (0.11)#	1.85 (0.17)*	0.86 (0.18)*	2.60 (0.20)*	−1.24 (0.14)*	−5.56 (0.40)*
4. Defecation pain	0.78*	0.64 (0.08)*	0.53 (0.10)*	1.97 (0.20)*	1.62 (0.21)*	1.75 (0.18)*	−1.53 (0.17)*	−5.57 (0.32)*
5. Difficult bowel movement	0.82*	0.68 (0.08)*	0.56 (0.10)*	2.46 (0.26)*	2.02 (0.25)*	3.31 (0.27)*	−0.67 (0.19)*	−5.26 (0.38)*
6. Abdominal distension	0.77*	0.54 (0.08)*	0.60 (0.08)*	1.57 (0.16)*	1.73 (0.18)*	2.13 (0.18)*	−1.36 (0.15)*	−6.12 (0.38)*
7. Reduced appetite	0.73*	0.43 (0.09)*	0.65 (0.08)*	1.17 (0.16)*	1.79 (0.19)*	0.31 (0.13)*	−2.51 (0.18)*	−5.52 (0.35)*
8. Dry mouth and throat	0.73*	0.25 (0.09)#	0.79 (0.05)*	0.78 (0.17)*	2.45 (0.22)*	1.44 (0.17)*	−2.07 (0.20)*	−6.06 (0.46)*
9. Sweaty palm and planta; distracted feeling	0.69*	0.13 (0.13)	0.88 (0.06)*	0.50 (0.25)#	3.35 (0.52)*	0.16 (0.20)*	−3.91 (0.51)*	−8.04 (0.98)*
10. Tea-colored urine, reduced urine volume	0.64*	0.22 (0.10)#	0.71 (0.06)*	0.57 (0.16)*	1.82 (0.18)*	0.62 (0.13)*	−2.75 (0.20)*	−6.70 (0.55)*

SE standard error. λ _i: factor i. a _i: discrimination parameter of dimension i. d _j: easiness parameter of category j of an item

^# P <0.05. *P <0.01