Table 5.

Reliability analysis of 25-item ADDQoL-Teen (whole sample)

Item	Scale mean if item deleted	Scale variance if item deleted	Corrected item-total correlation	Alpha if item deleted
1: others fuss	-44.67	1412.16	0.4881	0.9102
2: sweets	-44.33	1357.63	0.6016	0.9079
3: drink	-45.60	1429.77	0.5125	0.9103
4: eat	-44.56	1363.22	0.5800	0.9084
5: insulin	-44.50	1334.19	0.6447	0.9070
6: bleed	-44.37	1391.05	0.5024	0.9099
8: interrupt do	-44.56	1364.32	0.5632	0.9088
9: finger tests	-44.59	1385.38	0.4451	0.9114
10: control	-45.51	1426.39	0.3727	0.9121
11: moody	-44.35	1376.36	0.5240	0.9096
12: unwell	-44.19	1391.50	0.4842	0.9103
15: wake nights	-45.15	1423.99	0.5022	0.9102
16: lie in bed	-44.75	1404.51	0.3802	0.9127
17: miss events	-46.22	1442.99	0.4281	0.9114
18: low BG	-45.28	1430.58	0.4483	0.9109
19: high BG	-44.33	1392.77	0.5171	0.9096
20: worry future	-44.64	1377.43	0.5054	0.9100
21: career	-44.42	1364.17	0.5803	0.9084
22: different	-45.20	1362.36	0.7117	0.9062
23: not allowed	-44.55	1361.46	0.6364	0.9073
24: family life	-45.16	1372.68	0.6134	0.9078
25: responsibility	-45.50	1415.25	0.4332	0.9111
26: play sport	-45.26	1396.84	0.5138	0.9097
27: go toilet	-45.38	1422.21	0.5002	0.9102
28: social life	-44.09	1349.43	0.5856	0.9083

Alpha = 0.9129, standardised item alpha = 0.9144 (N = 133).