Significant between-group differences were observed for change in confidence in knowledge ( mean difference 8.51 ; 95 % confidence interval [ 95 % CI ] 6.29 , 10.73 ; effect size 1.62 ) and skills ( mean difference 7.26 ; 95 % CI 5.1 , 9.4 ; effect size 1.54 ) , with the intervention group performing better .