For the graphs below, match the graph to the description below. (2 each)

a.) Which graph below indicates a negative correlation?

b.) Which graph indicates that X^{2} should be added to the regression model?

c.) Which graph suggests the regression fit is "as good as it gets"?

d.) Which graph suggests a transformation such as In(Y) versus X is the appropriate regression model?

**Solution: **

**(a) #3**

**(b) #4**

**(c) #3**

**(d) #2**

## Stats Solution Summary

Observe that it is usually possible to assess the degree of the linear relationship between two variables by looking at the corresponding scatterplot. A linear association is indicated by having the points of the scatterplot relatively tightly assembled around a line.

A lack of a pattern, or the existence of a non-linear, curvilinear pattern would be an indication of a lack of a linear association.

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