title: Power of the classical twin design revisited: II detection of common environmental variance.
abstract: We expand our previous deterministic power calculations by calculating the required sample size to detect C in ACE models. The theoretical expected value of the maximum log-likelihood for the AE model was derived using two optimisation methods and these gave near-identical results. Theoretical predictions were verified by computer simulation and the results agreed very well. We have developed a user-friendly web-based tool, TwinPower, to perform power calculations to detect either A or C for the classical twin design. This new tool can be found at http://genepi.qimr.edu.au/cgi-bin/twinpower.cgi.
authors.affiliation: Genetic Epidemiology, Queensland Institute of Medical Research, Brisbane, Australia. peter.visscher@qimr.edu.au
authors.forename: Peter M
authors.initials: PM
authors.lastname: Visscher
authors.forename: Scott
authors.initials: S
authors.lastname: Gordon
authors.forename: Michael C
authors.initials: MC
authors.lastname: Neale
mesh_terms: D003198:Computer Simulation; D004777:Environment; D016013:Likelihood Functions; D008962:Models, Theoretical; D012107:Research Design; D012984:Software; D018433:Twin Studies as Topic