# Exploring Other Function Models

### Resources for this lesson:

> Glossary

> Calculator Resources

> Teacher Resources: Instructional Notes

After inspecting the residuals, Khalid notices that the residuals are very close to zero and do not show a pattern. So, a cubic regression is an excellent fit for the data set.

Just to be sure, he decides to calculate a quartic regression. Here is the quartic regression equation:

Khalid: For this regression equation, the leading coefficient is close to 0. When this happens for a polynomial function, it indicates that the best fit is one degree less. So, the cubic function is in fact the best fit for the data.