what is pca and how to deal with it why use pca what is the purpose of pca how to do pca with zero spikes what are the variables that should be used in pca what is pca pca what type of variables do you use in a pca analysis can pca use zero spike what type of data is affected by zero spike variables? which variables are pca's when using pca what type of variables are used when to use pca with zero spike do you need to use pca to reduce pca when using pca with zero spike variables what is pca with negative variance what kind of variables can i use for pca why use pca for variables which variables are non-responsive to pca when to use pca with zero spike which variable is considered a negative pca?