The correct answer is: C. QQ
A residual plot is a graph of the residuals (the difference between the observed values and the fitted values) against the fitted values. Residual plots can be used to investigate the normality of the errors, the linearity of the relationship between the independent and dependent variables, and the homoscedasticity of the errors.
A QQ plot is a type of residual plot that is used to investigate the normality of the errors. A QQ plot is a scatterplot of the standardized residuals against the theoretical quantiles of a normal distribution. If the errors are normally distributed, the points in the QQ plot should fall close to a straight line.
The other options are incorrect because they are not types of residual plots.
- A. RR plots are residual vs. response plots. These plots can be used to investigate the linearity of the relationship between the independent and dependent variables.
- B. PP plots are probability plots. These plots can be used to investigate the normality of the residuals.
- D. None of the mentioned is also incorrect because it is not a type of residual plot.