## Adding Curves

You can add curves to a scatter plot in the fit window in two
ways. You can choose from the **Curves** menu or you can select
**Edit:Windows:Renew** to reset the fit output options.
When you add a curve from the **Curves** menu, SAS/INSIGHT adds
either a new table entry or a whole new table that contains
a summary of the new curve fit.
Suppose you want to compare polynomial fits of different
degree directly on the scatter plot. Begin by adding a
second polynomial fit to the plot.
| Choose **Curves:Polynomial**. |

**Figure 13.8:** Curves Menu

This displays the polynomial fit dialog
shown in Figure 13.9.

**Figure 13.9:** Polynomial Fit Dialog

| Set the degree for the new polynomial to **3** and click **OK**. |

This adds a cubic polynomial fit to the scatter plot, as shown in
Figure 13.10.

Now you have two polynomial fits in the window.
Note that an entry for the cubic polynomial has been
added to the **Parametric Regression Fit** table.
Each entry in the table has its own slider so that
you can adjust the degree of either polynomial to
compare any pair of fits.

**Figure 13.10:** Fit Window with Two Polynomial Fits

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