what is covariance based pca what is the difference between principal component analysis and covariance correlation can a correlation matrix be used for a correlation matrix does correlation based pca work what is the difference between correlation matrix and covariance matrix when using pca do variables scale separately? what is the difference between covariance matrix and correlation matrix? what is principal component analysis is correlation based pca what is covariance matrix for pca which approach is best for pca? what is the difference between a correlation matrix and a covariance matrix? which approach is correct when the variance of the data is standardized? what is the difference between correlation matrix and covariance matrix can you use the correlation matrix for pca does correlation and covariance make good pca does correlation based pca work does pca make sense what is the correct pca technique for pca why is pca not correctly used