I'm following along with the vignette for CQN and I encountered a message which I don't understand. When using the cqn function the SQN package it calls states that it is using 'sigma' instead of 'sig2'. I'm not sure what this means, or what affect this has on the results of the cqn package, or its downstream use in edgeR and DEseq2.

> cqn <- cqn(countMatrix, lengths=uCovar$length, x=uCovar$gccontent, sizeFactors = sizeFactors, verbose=TRUE)
RQ fit ..................................
SQN Using 'sigma' instead 'sig2' (= sigma^2) is preferred now