When a Black Belt performs a Simple Linear Regression and observes the Residuals versus Fits plot, he observes two points shooting way out of the 0 Residual mark. What is the important thing he should infer?
OPTIONS
- That the data may be incorrect
- That the data may suffer from a lack of fit
- That the data may be an effect of special cause variability
- That the data needs treatment
ANSWER
That the data may be an effect of special cause variability
EXPLANATION
Graphical analysis of a residual plot needs all the points close to the 0 mark to show that variation is due chance. Off-shooting the 0 mark indicates special causes, so c is correct.
