Standardized residuals are residuals expressed in what units?

• A. The original measurement units of the dependent variable.
• B. Standard deviation units.
• C. The fitted value units.
• D. The squared residual units.

Answer: (D)

Standardized residuals express each residual in standard deviation units. You take the difference between the observed value and the model’s fitted value (the residual) and divide it by an estimate of the residuals’ standard deviation. This puts the residuals on a common scale with a mean around zero and a standard deviation around one, so you can judge how unusual a residual is by comparing it to typical z-values (about ±2 or ±3). They are not measured in the original units of the dependent variable, nor in the fitted value units, and they are not in squared units. This standardization helps reveal outliers and assess whether residuals behave like they should under the model.