Table 3.

Comparison of mean scores of each core aspect of MI training between questionnaires completed before and after the training sessions (exact Wilcoxon-Pratt signed-rank tests).

	Score pre-session 1	Score difference between post-session 1 and pre-session 1			Score difference between post-session 2 and pre-session 1			Score difference between post-session 2 and post-session 1
	mean ± SD	mean ± SD	Pr ≥ |Z|	Effect size r	mean ± SD	Pr ≥|Z|	Effect sizer	mean ± SD	Pr ≥ |Z|	Effect size r
Knowledge acquisition (/100) (n = 43, 35, 34, respectively)	54.0 ± 22.2	21.1 ± 21.6	<.0001	0.73 [0.59;0.84]	21.7 ± 17.7	<.0001	0.82 [0.75;0.86]	2.5 ± 10.2	0.27	0.23 [0.01;0.53]
Perception of application of MI skills(/100) (n = 43, 34, 34, resp.)	30.0 ± 22.7	36.8 ± 36.7	<.0001	0.72 [0.54;0.83]	38.5 ± 31.9	<.0001	0.80 [0.64;0.87]	−3.4 ± 29.9	0.16	0.24 [0.02;0.59]
Self-confidence in applying MI(/100) (n = 42, 33, 34, resp.)	40.6 ± 10.6	21.2 ± 11.1	<.0001	0.87 [0.86;0.87]	28.7 ± 25.4	<.0001	0.87 [0.87;0.87]	6.5 ± 24.2	0.07	0.31 [0.03;0.58]
Skills assessed with written dialogue(n = 43, 34, 34, resp.) [min;max] = [0;12 pre] [2;16 post-session 1] [2;14 post-session 2])	4.6 ± 2.8	4.2 ± 2.9	<.0001	0.83 [0.75;0.87]	3.3 ± 3.2	<.0001	0.73 [0.52;0.87]	−0.9 ± 3.4	0.24	0.20 [0.01;0.51]

The effect size (r) value varies from 0 to close to 1. Values of r: 0.10 - < 0.3 (small effect); 0.30 - < 0.5 (moderate effect); > = 0.5 (large effect).

Interpretation: knowledge acquisition score increased by 21 points between post- and pre-session 1; session 1 had a large effect on the change in the score (r = 0.73).