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Power of the Classical Twin Design Revisited: II Detection of Common Environmental Variance

Published online by Cambridge University Press:  21 February 2012

Peter M. Visscher ,
Scott Gordon  and
Michael C. Neale
Peter M. Visscher*
Affiliation:
Genetic Epidemiology, Queensland Institute of Medical Research, Brisbane, Australia. peter.visscher@qimr.edu.au
Scott Gordon
Affiliation:
Genetic Epidemiology, Queensland Institute of Medical Research, Brisbane, Australia.
Michael C. Neale
Affiliation:
Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, Virginia, United States of America.
*
*Address for correspondence: Peter M. Visscher, Genetic Epidemiology, Queensland Institute of Medical Research, PO Royal Brisbane Hospital, QLD 4029, Australia.

Abstract

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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

Type
Articles
Information
Twin Research and Human Genetics , Volume 11 , Issue 1 , 01 February 2008 , pp. 48 - 54
Copyright
Copyright © Cambridge University Press 2008