This function is designed to calculate the overall variance for cluster-level outcomes in a mixedeffect Poisson model. Conditional expectation calculations are implemented.
mixed.eff.params(pi0, btw.clust.var, Tk)
the baseline cluster-level mean on the scale of the link function
the at-risk time for each cluster
mixed.eff.params() function is used by the
hayes.power.poisson() function to
compute the effective coefficient of variation, or k, for a particular
A numeric vector with the following three named elements, in order: ["expectation"] the overall mean of cluster-level outcomes, ["variance"] the overall variance of cluster-level outcomes, ["hayes.k"] the estimated coefficient of variation.
Nicholas G. Reich
Reich NG et al. PLoS ONE. Empirical Power and Sample Size Calculations for Cluster-Randomized and Cluster-Randomized Crossover Studies. 2012. http://ow.ly/fEn39
Hayes RJ and Bennett S. Int J Epi. Simple sample size calculation for cluster-randomized trials. 1999. http://www.ncbi.nlm.nih.gov/pubmed/10342698
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