Table I.

Power and sample size equations for models (3)–(6) assuming CS covariance of both response and exposure, and constant exposure prevalence. For models (3), (5) and (6), all participants are assumed to enter the study at the same time (V (t₀) = 0). For model (3), all participants are assumed to be unexposed at baseline $(E_{i,-1}^{*}=0\forall i)$.

	Power formula: $\pi =\mathrm{\Phi }[\sqrt{N}|\gamma |/\mathrm{\sigma ̃}-z_{1-\alpha /2}]$
	Sample size formula: N = σ̃2 (zπ + z1−α/2)2/γ2
Model	Parameter of interest	σ̃2
(3)	γe*	$\frac{12{\sigma }^2(1-\rho )(1+r\rho )}{p_e(1-p_e)(r+1)(r+2)[6+2(r-3)\rho +r(4+(r-5)\rho ){\rho }_e]}$
(4)	${\gamma }_{e*}^W$	$\frac{12{\sigma }^2(1-\rho )}{p_e(1-p_e)s^{2}r(r+2)[2+(r-1){\rho }_e]}$
(5)	γte	$\frac{12{\sigma }^2(1-\rho )(1+r\rho )}{p_e(1-p_e)s^{2}r(r+1)(r+2)[1+r\rho -\rho (1-{\rho }_e)]}$
(6)	${\gamma }_{te}^W$	$\frac{12{\sigma }^2(1-\rho )}{p_e(1-p_e)s^{2}r(r+{\rho }_e)(r+2)}$