R has a DModX Calculation for PCA. I've seen references in some online texts that a critical DModX can be used to flag samples which are significantly poor fit to the model. The R documentation states that DModX is approximately F-distributed. How would I use the F Distribution to calculate the critical DModX value at a particular confidence interval given my PCA model? It seems there are several definitions of DModX in different software packages, each using different scaling parameters. Sticking to the definition used in R would be appreciated.