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There's nothing ad hoc about it - PCA is an extremely fundamental statistical tool, and commonly used in genetics, especially to evaluate population structure.

There's nothing ad hoc about it - PCA is an extremely fundamental statistical tool, and commonly used in genetics, especially to evaluate population structure. A few random examples: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3392282/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3392282/ https://speciationgenomics.github.io/pca/ https://speciationgenomics.github.io/pca/ https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.0020190 https://journals.plos.org/plosgenetics/article?id=10.1371/jo... https://www.genetics.org/content/210/2/719 https://www.genetics.org/content/210/2/719 https://www.nature.com/articles/ng0508-491 https://www.nature.com/articles/ng0508-491 If that SSC reference bothers you so much, you can look at the Atlantic for a definition of weak man instead: https://www.theatlantic.com/daily-dish/archive/2009/07/the-weak-man-argument/199263/ https://www.theatlantic.com/daily-dish/archive/2009/07/the-w... And I know what intrinsic means, but I don't know what an "intrinsic point" is supposed to be, or what makes my point "intrinsic", as opposed to just a regular point.

throrthaway 6y ago
Yes you don't need to explain my field to me, thank you very much. Are you going to post wikipedia links next? It still doesn't change the fact that PCA is extremely unrigorous for any analysis that goes beyond 'looking at pretty figures'. The vectors are literally and utterly meaningless. They're selected in an ad hoc way for each dataset. If you want to untangle population structure properly there are countless other more rigorous methods, although they are not without their flaws. But the fact that you want to use PC1 and PC2 plots to prove a weird point about ethnicity makes me think you either don't know what you're talking about and are just using the field as a front to advance your weird beliefs. Even Steve Hsu would be more rigorous than that

throrthaway 6y ago

Yes you don't need to explain my field to me, thank you very much. Are you going to post wikipedia links next? It still doesn't change the fact that PCA is extremely unrigorous for any analysis that goes beyond 'looking at pretty figures'. The vectors are literally and utterly meaningless. They're selected in an ad hoc way for each dataset. If you want to untangle population structure properly there are countless other more rigorous methods, although they are not without their flaws. But the fact that you want to use PC1 and PC2 plots to prove a weird point about ethnicity makes me think you either don't know what you're talking about and are just using the field as a front to advance your weird beliefs. Even Steve Hsu would be more rigorous than that