how far apart are the two groups using pca how to separate groups using a pca what is the first pca on a group how many patients in a group with a pca how to separate pca groups does pca work for patients does pca divide groups pca of controls and patients definition how far apart are groups using pca how many groups do you separate with pca how to separate groups by pca how do i separate normal control groups what is pca in patients how to separate patients between groups how do you separate groups with pca how to separate patients and patients using pca how do i separate pca groups how to separate the groups for pca how to separate patients into groups using pca what would the value of a pca show in two groups