Residuals are used to check a linear model's assumptions. From SAS Help 'The MIXED Procedure: Residuals and Influence Diagnostics' section we know that there are different types of residuals (Table 58.21 Residual Types Computed by the MIXED Procedure). Which one should we use? What does it mean 'internally' or 'externally' processed? What does 'standardization' mean? What kind of residuals we can calculate with the B formula in my previous question?