This Shiny application provides automated power analysis for the detection of additive genetic (A) and common environmental (C) variance components of a quantitative trait in the classical twin design.

Adjust the parameters on the left and press calculate to view the results


ACE vs. CE model
ACE vs. AE model


NCP: Noncentrality parameter, ML: Maximum likelihood, E: Environmental variance component, MZ: Monozygotic, DZ: Dizygotic

If you use this site, please reference the following: Visscher P.M. (2004). 'Power of the classical twin design revisited'. Twin Research 7, 505-512 and Visscher P.M., Gordon S., Neale M.C. (2008) and 'Power of the classical twin design revisited: II Detection of Common Environmental Variance'. Twin Research and Human Genetics 11, 48-54.

Please send suggestions or comments to Peter Visscher or if you are having difficulties with the application please contact Luke Lloyd-Jones at This application was prepared by Matthew Robinson, Luke Lloyd-Jones and Peter Visscher.