# How to extract MSEP or RMSEP from lassoCV?

I'm doing lasso and ridge regression in R with the package chemometrics. With ridgeCV it is easy to extract the SEP and MSEP values by modell.ridge$RMSEP and model.ridge$SEP. But how can I do this with lassoCV? model.lasso$SEP works, but there is no RMSE or MSE entry in the list. However the function provides a plot with MSEP and SEP in the legend. Therefore it must be possible to extract both values! But how? • SEP = standard error of the predictions; • MSEP = mean squared error of the predictions; • RMSEP = root mean square error of the predictions = root(MSEP) • What do SEP, MSEP and RMSEP stand for? Mar 17 at 18:21 • Please provide the definitions of those abbreviations by editing the question, as comments are easy to overlook and can get deleted. – EdM Mar 17 at 20:09 ## 1 Answer After doing lassoCV model.lasso <- lassoCV(y ~ x, ...)  one can extract the MSE values by model.lasso$cv[model.lasso$ind] and therefore calculate the RMSE too sqrt(model.lasso$cv[model.lasso\$ind]).

Based on the documentation cv extracts the MSEP values at each value of fraction and ind is the index of fraction with optimal choice for fraction.