HH.count: Power calculation for count outcome based on analytic formula...

In giabaio/SWSamp: Computes Sample Size for a Stepped Wedge Design, using Simulation-Based Calculations

Power calculation for count outcome based on analytic formula of Hussey and Hughes

Description

Sample size calculations for count outcomes based on the formula provided by Hussey and Hughes (2007)

Usage

HH.count(
  lambda1,
  RR,
  I,
  J,
  K,
  rho = 0,
  sig.level = 0.05,
  which.var = "within",
  X = NULL
)

Arguments

lambda1	Baseline value for the rate at which the outcome occurs
RR	Relative risk (of the intervention vs the control)
I	Number of clusters
J	Number of time points
K	Average size of each cluster
rho	Intra-class correlation coefficient (default=0)
sig.level	Significance level (default=0.05)
which.var	String character specifying which variance to be considered (options are the default value 'within' or 'total'
X	A design matrix for the stepped wedge design, indicating the time at which each of the clusters should switch the active intervention. By default is NULL and automatically computed, but can be passed as an extra argument as a user-defined matrix with I rows and (J+1) columns

Value

power	The resulting power
sigma.y	The estimated total (marginal) sd for the outcome
sigma.e	The estimated residual sd
sigma.a	The resulting cluster-level sd
setting	A list including the following values: - n.clusters = The number of clusters - n.time.points = The number of 'active' time points - avg.cluster.size = The average cluster size - design.matrix = The design matrix for the SWT under consideration

Author(s)

Gianluca Baio

References

Baio, G; Copas, A; Ambler, G; Hargreaves, J; Beard, E; and Omar, RZ Sample size calculation for a stepped wedge trial. Trials, 16:354. Aug 2015.

Hussey M and Hughes J. Design and analysis of stepped wedge cluster randomized trials. Contemporary Clinical Trials. 28(2):182-91. Epub 2006 Jul 7. Feb 2007

Examples

HH.count(lambda1=1.55,RR=.87,I=10,J=5,K=20,rho=.2)

giabaio/SWSamp documentation built on Nov. 14, 2022, 2:24 p.m.