I have been enjoying using mixOmics package and as I dive deeper into my analysis, I had more questions.
According to some papers on PLSDA (e.g.https://link.springer.com/article/10.1007/s11306-011-0330-3), a double cross-validation scheme may be the most unbiased way to validate the PLSDA model. I noticed that I can perform cross-validation through both the perf() and the tune() function in the mixOmics package. Is the cross-validation implemented in these two functions a double cross-validation scheme? Will the number of folds affect the error rate? And how should I determine the number of folds?