By default, Evince uses UV scaling (unit variance scaling) when preparing a DataSet prior to creating a multivariate PCA or PLS model. UV scaling means that all variables are divided by their standard deviations. This implies that all variables have equal variation of one unit. For certain kinds of data, e.g. when variables have different units, this can improve the modeling as some variables with large variation would otherwise influence the models. For other kinds of data, e.g. when variables consists of spectral measurements, unit variance scaling will make the noise more prominent, thus making the modeling more difficult.

UV scaling is almost always used in conjunction with variable mean centering.