6-Item short form summary score to T-score concordance table

Summary	Theta score	T-score
6	–3.00	20.0
7	–2.62	23.8
8	–2.35	26.5
9	–2.11	28.9
10	–1.90	31.0
11	–1.71	32.9
12	–1.53	34.7
13	–1.36	36.4
14	–1.20	38.0
15	–1.04	39.6
16	–.89	41.1
17	–.74	42.6
18	–.59	44.1
19	–.44	45.6
20	–.29	47.1
21	–.14	48.6
22	.02	50.2
23	.18	51.8
24	.34	53.4
25	.51	55.1
26	.69	56.9
27	.90	59.0
28	1.13	61.3
29	1.41	64.1
30	1.89	68.9

All 6 items are summed as a first step. After summing, scores are transformed to a T-score metric using the concordance table provided above. For comparison purposes, the mean in the development sample was 49.9 with a SD of 9.3