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Chapter 7: Getting Ahead of the Learning Curve with Nonlinear Regression 121

polynomials, refer to your algebra textbook or Algebra For Dummies by Mary
Jane Sterling (Wiley).

y

7
6
rises right
5
falls left 4
3
2
1
x
−7 −6 −5 −4 −3 −2 −1 −1 1 2 3 4 5 6 7
−2
Figure 7-4: −3
Example −4
of a third- −5
degree −6
polynomial. −7

The nonlinear models in this chapter involve only one explanatory variable, x.
You can include more explanatory variables in a nonlinear regression, raising
each separate variable to a power, but those models are beyond the scope of this
book. I give you information on basic multiple regression models in Chapter 5.

y
rises right
7
6
5
4
rises left 3
2
1
x
−7 −6 −5 −4 −3 −2 −1 1 2 3 4 5 6 7
−1
−2
Figure 7-5: −3
Example of −4
a fourth- −5
degree −6
polynomial. −7

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