The Diabetes Self-Management Questionnaire (DSMQ): development and evaluation of an instrument to assess diabetes self-care activities associated with glycaemic control

Table 3 Distribution of scores, item difficulties, scale-correlations, internal consistency in case of deletion, and correlations with HbA _1c of the DSMQ items

Item	Distribution of item scores	Difficulty index^a	Item-subscale-correlation^b	Item-total-correlation^b	α if item deleted	Correlation with HbA_1c
1	2.28 ± 0.90	78.9	0.69	0.59	0.82	−0.35‡
2	1.56 ± 0.82	53.3	0.58	0.62	0.82	−0.28‡
3	2.68 ± 0.65	94.3	0.42	0.32	0.83	−0.20†
4	2.76 ± 0.55	96.2	0.53	0.49	0.83	−0.27‡
5	1.62 ± 1.04	45.2	0.62	0.46	0.83	−0.17†
6	1.97 ± 1.12	65.9	0.49	0.47	0.83	−0.24‡
7	2.67 ± 0.63	6.5	0.44	0.35	0.83	−0.19†
8	1.36 ± 0.93	44.4	0.52	0.39	0.83	−0.09
9	1.43 ± 0.85	43.7	0.60	0.51	0.82	−0.16†
10	1.99 ± 1.07	31.4	0.60	0.55	0.82	−0.33‡
11	2.04 ± 1.01	31.4	0.70	0.41	0.83	−0.15*
12	2.31 ± 0.96	19.5	0.48	0.40	0.83	−0.30‡
13	1.91 ± 1.04	36.4	0.50	0.50	0.82	−0.30‡
14	2.15 ± 0.98	26.8	0.43	0.26	0.84	−0.20†
15	1.83 ± 1.03	38.7	0.55	0.28	0.84	−0.11
16	1.91 ± 1.01	33.7	n/a	0.69	0.81	−0.38‡

Data are M ± SD, difficulty indices, Pearson’s correlations, Cronbach’s α or Spearman’s ρ.
Correlations with HbA_1c are Spearman’s ρ; * P < 0.05; † P < 0.01; ‡ P < 0.001 (two-tailed test).
^a percentage of agreements among all responses.
^b part-whole-corrected.

ISSN: 1477-7525