Power of the classical twin design revisited: II detection of common environmental variance.
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.
Visscher
Peter M
PM
Genetic Epidemiology, Queensland Institute of Medical Research, Brisbane, Australia. peter.visscher@qimr.edu.au
Gordon
Scott
S
Neale
Michael C
MC
D003198:Computer Simulation; D004777:Environment; D016013:Likelihood Functions; D008962:Models, Theoretical; D012107:Research Design; D012984:Software; D018433:Twin Studies as Topic