Math 143 C/E, Spring 2001
IPS Reading Questions
Chapter 2, Section 4

1. Figure 2.18(b) is a residual plot for the fitted line in Figure 2.18(a). Is there any way to ``visualize" (b) looking only at (a)?

   
   
   
   
   
   
   
   
   
   
   

2. Suppose that a certain scatterplot reveals what appears to be a linear relationship between the explanatory and response variables. Explain the difference between outliers and influential observations. How might you determine which observations are influential and which ones are not?

   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

3. In the blue box on p. 166, the authors emphasize that ``association does not imply causation". In what situations would you be fairly safe in saying that association does imply causation?