trafo

Estimation, selection and comparison of several families of transformations. The families of transformations included in the package are the following: Bickel-Doksum (Bickel and Doksum 1981 doi:10.2307/2287831), Box-Cox, Dual (Yang 2006 doi:10.1016/j.econlet.2006.01.011), Glog (Durbin et al. 2002 doi:10.1093/bioinformatics/18.suppl_1.S105), gpower (Kelmansky et al. 2013 doi:10.1515/sagmb-2012-0030), Log, Log-shift opt (Feng et al. 2016 doi:10.1002/sta4.104), Manly, modulus (John and Draper 1980 doi:10.2307/2986305), Neglog (Whittaker et al. 2005 doi:10.1111/j.1467-9876.2005.00520.x), Reciprocal and Yeo-Johnson. The package simplifies to compare linear models with untransformed and transformed dependent variable as well as linear models where the dependent variable is transformed with different transformations. Furthermore, the package employs maximum likelihood approaches, moments optimization and divergence minimization to estimate the optimal transformation parameter.