TABLE 3.

Definition of intracluster correlation coefficients (ICCs) under a closed-cohort design with total variance for the l-th outcome denoted by ${\sigma }_{\mathit{Y}l}^2={\sigma }_{bl}^2+{\sigma }_{sl}^2+{\sigma }_{\gamma l}^2+{\sigma }_{ϵl}^2$.

ICC	Definition	Expression
${\rho }_0^l$	within-period endpoint-specific ICC	$\mathrm{corr}\left({\mathit{Y}}_{ijkl},{\mathit{Y}}_{ij{k}^{\prime }l}\right)=\left({\sigma }_{bl}^2+{\sigma }_{sl}^2\right)/{\sigma }_{\mathit{Y}l}^2$
${\rho }_1^l$	between-period endpoint-specific ICC	$\mathrm{corr}\left({\mathit{Y}}_{ijkl},{\mathit{Y}}_{i{j}^{\prime }{k}^{\prime }l}\right)={\sigma }_{bl}^2/{\sigma }_{\mathit{Y}l}^2$
${\rho }_0^{l{l}^{\prime }}$	within-period between-endpoint ICC	$\mathrm{corr}\left({\mathit{Y}}_{ijkl},{\mathit{Y}}_{ij{k}^{\prime }{l}^{\prime }}\right)=\left({\sigma }_{bl{l}^{\prime }}+{\sigma }_{sl{l}^{\prime }}\right)/\left({\sigma }_{\mathit{Y}l}{\sigma }_{\mathit{Y}{l}^{\prime }}\right)$
${\rho }_1^{l{l}^{\prime }}$	between-period between-endpoint ICC	$\mathrm{corr}\left({\mathit{Y}}_{ijkl},{\mathit{Y}}_{i{j}^{\prime }{k}^{\prime }{l}^{\prime }}\right)={\sigma }_{bl{l}^{\prime }}/\left({\sigma }_{\mathit{Y}l}{\sigma }_{\mathit{Y}{l}^{\prime }}\right)$
${\rho }_{2,0}^{l{l}^{\prime }}$	within-period intra-subject ICC	$\mathrm{corr}\left({\mathit{Y}}_{ijkl},{\mathit{Y}}_{ijk{l}^{\prime }}\right)=\left({\sigma }_{bl{l}^{\prime }}+{\sigma }_{sl{l}^{\prime }}+{\sigma }_{\gamma l{l}^{\prime }}+{\sigma }_{ϵl{l}^{\prime }}\right)/\left({\sigma }_{\mathit{Y}l}{\sigma }_{\mathit{Y}{l}^{\prime }}\right)$
${\rho }_{2,1}^{l{l}^{\prime }}$	between-period intra-subject ICC	$\mathrm{corr}\left({\mathit{Y}}_{ijkl},{\mathit{Y}}_{i{j}^{\prime }k{l}^{\prime }}\right)=\left({\sigma }_{bl{l}^{\prime }}+{\sigma }_{\gamma l{l}^{\prime }}\right)/\left({\sigma }_{\mathit{Y}l}{\sigma }_{\mathit{Y}{l}^{\prime }}\right)$
${\rho }_2^l$	intra-subject endpoint-specific ICC	$\mathrm{corr}\left({\mathit{Y}}_{ijkl},{\mathit{Y}}_{i{j}^{\prime }kl}\right)=\left({\sigma }_{bl}^2+{\sigma }_{\gamma l}^2\right)/{\sigma }_{\mathit{Y}l}^2$