RE: newbie question

2004-03-11 Thread Clay Corbin
I've done it after bootstrapping eigen coefficients so that I have some confidence in a rejection of isometry when dealing with multiple groups (Common PCAs). I've got an unpublished manuscript (revising it now actually) explaining my methods if you would like to see it. But, you can probably als

RE: newbie question

2004-03-10 Thread morphmet
I've seen this "normalization" before (although I don't remember where - probably in 1980s physical anthropology papers). As Dr. Rohlf notes, the only real point of dividing PC1 eigenvector coefficients by the isometric expectation (1 over sqrt of the number of measurements) to put them into more

RE: newbie question

2004-03-10 Thread morphmet
I guess what is meant is the fact that if you compute a normalized PC1 from a correlation matrix based on p variables for data in which PC1 represents size and growth is isometric then the loadings will all be equal to 1/sqrt(p). That is because "normalized" means that the sum of the squared elemen