an optional character string specifying the type of
residuals to be used. If `"response"`

, the "raw" residuals
(observed - fitted) are used; else, if `"pearson"`

, the
standardized residuals (raw residuals divided by the corresponding
standard errors) are used; else, if `"normalized"`

, the
normalized residuals (standardized residuals pre-multiplied by the
inverse square-root factor of the estimated error correlation
matrix) are used. Partial matching of arguments is used, so only the
first character needs to be provided. Defaults to `"response"`

.