Table 2. Discrimination (a) parameters for the graded MIRT model used in calibrated projection of PAIS scores from responses to the PedsQL™ asthma symptoms scale.

Item		a1	a2	a3	a4	a5	a6	a7	a8
PAIS—17 items
8	I had trouble breathing because of my asthma	2.92	0	0	0	0	0	0	0
9	My asthma bothered me	2.65	0	0	0	0	0	0	0
10	It was hard for me to play sports or exercise because of my asthma	2.03	0	0	0	0	0	0	0
6	My chest felt tight because of my asthma	2.00	0	0	0	0	0	0	0
16	I had trouble walking because of my asthma	1.95	0	0	0	0	0	0	0
5	I felt scared that I might have trouble breathing because of my asthma	1.93	0	0	0	0	0	0	0
4	My body felt bad when I was out of breath	1.84	0	0	0	0	0	0	0
3	I was bothered by the amount of time I spent wheezing	1.78	0	0	0	0	0	0	0
2	My asthma bothered me when I was with my friends	1.53	0	0	0	0	0	0	0
17	I missed school because of asthma	1.47	0	0	0	0	0	0	0
1	I got tired easily because of my asthma	1.37	0	0	0	0	0	0	0
13	I had asthma attacks	3.89	0	3.85	0	0	0	0	0
12	I felt wheezy because of my asthma	3.86	0	0	2.37	0	0	0	0
15	It was hard to take a deep breath because of my asthma	3.49	0	0	0	2.04	0	0	0
7	It was hard for me to play with pets because of my asthma	2.99	0	0	0	0	4.06	0	0
11	I had trouble sleeping at night because of my asthma	2.79	0	0	0	0	0	1.66	0
14	I coughed because of my asthma	2.76	0	0	0	0	0	0	2.52
PedsQL asthma symptoms scale—11 items
20	I have asthma attacks	0	4.09	3.85	0	0	0	0	0
19	I feel wheezy	0	3.90	0	2.37	0	0	0	0
24	It is hard to take a deep breath	0	3.42	0	0	2.04	0	0	0
27	It is hard for me to play with pets	0	3.36	0	0	0	4.06	0	0
26	I wake up at night with trouble breathing	0	3.11	0	0	0	0	1.66	0
23	I cough	0	2.63	0	0	0	0	0	2.52
18	My chest hurts or feels tight	0	2.31	0	0	0	0	0	0
22	I get out of breath	0	2.25	0	0	0	0	0	0
28	It is hard for me to play outside	0	2.19	0	0	0	0	0	0
21	I get scared when I have asthma attacks	0	1.70	0	0	0	0	0	0
25	I have a stuffy or runny nose	0	1.07	0	0	0	0	0	0