changes in version 1.9.1 *modified package so that normalization function does not output data when any model parameters are not possible to estimate. *added function metabPlot to plot pre vs. post normalization metabolite abundances. *updated mixnorm vignette changes in version 1.7.3 *modified package functions to handle situations where metabolites are entirely missing for all levels of a categorical predictor in the mixture model. changes in version 1.7.1 *modified package functions to handle situations where metabolites are entirely missing for a particular level of a categorical predictor in the mixture model. changes in version 1.3.6 *made small modifications to arguments for function mixnorm *added vignette for mixnorm changes in version 1.3.1 *added mixnorm function for normalization of non-targeted metabolomics studies