Table 3.

IRT Parameters

Suspiciousness and Paranoid Ideation
Item	Item Content	White		Black		Severity Difference
		† Severity	‡ Discrim	† Severity	‡ Discrim
9	I am sure I am being talked about behind my back.	0.53	2.80	0.25	2.70	−0.28
18	Do you often feel that other people have it in for you?	0.81	4.48	0.49	4.06	−0.32
27	Do you sometimes get concerned that friends or coworkers are not really loyal or trustworthy?	0.12	1.66	−0.15	2.02	−0.27
36	I feel I have to be on my guard even with friends.	0.43	3.62	0.03	2.84	−0.40
44	Do you often pick up hidden threats or put-downs from what people say or do?	0.58	2.32	0.55	2.63	−0.03
52	Have you found that it is best not to let other people know too much about you?	−0.05	2.83	−0.83	1.81	−0.78
59	I often feel that others have it in for me.	0.82	6.68	0.58	3.73	−0.24
65	Do you often have to keep an eye out to stop people from taking advantage of you?	0.32	2.21	−0.06	2.49	−0.38
Ideas of Reference
Item	Item Content	White		Black		Severity Difference
		† Severity	‡ Discrim	† Severity	‡ Discrim
1	Do you sometimes feel that things you see on the TV or read in the newspaper have a special meaning for you?	0.38	1.59	0.12	1.03	−0.26
10	I am aware that people notice me when I go out for a meal or to see a film.	0.59	1.81	0.27	1.78	−0.32
19	Do some people drop hints about you or say things with a double meaning?	0.60	2.02	0.36	2.44	−0.24
28	Have you ever noticed a common event or object that seemed to be a special sign for you?	0.47	1.50	0.50	1.53	0.03
37	Do you sometimes see special meanings in advertisements, shop windows, or in the way things are arranged around you?	1.03	1.57	0.77	1.21	−0.26
45	When shopping do you get the feeling that other people are taking notice of you?	0.54	2.36	0.28	2.70	−0.26
53	When you see people talking to each other, do you often wonder if they are talking about you?	0.67	3.19	0.44	3.59	−0.23
60	Do you sometimes feel that other people are watching you?	0.39	3.70	0.06	4.13	−0.33
63	Do you sometimes feel that people are talking about you?	0.30	2.89	0.16	4.94	−0.14

^†Severity is the latent trait level at which participant group is likely to start endorsing yes to an item above 50% likelihood.

^‡Discrim. is the discrimination parameter (analogous to factor loading) indicates an item’s ability to differentiate participants.