A two-year comparative assessment of retention of arch width increases between modified vacuum-formed and Hawley retainers: a multi-center randomized clinical trial

Table 1 Intra-class correlation coefficient in the arch width measurements

ICC	n	Coefficient	95% confidence interval		P value
ICC	n	Coefficient	Lower bound	Upper bound	P value
Intra-rater reliability	20	1.00	1.00	1.00	< .001*
Inter-rater reliability	20	0.98	0.53	1.00	< .001*

ICC indicates intra-class correlation coefficient; n, sample size; *, statistical significance