1. Fitting Exponentials and Polynomials to Data
Lesson 9.7

2. Linear Regression
Used in section 1.6 to find equation for a line of best fit
Used in section 4.4 to find equations of logarithmic models
Other types of regression are available

3. Problem … Which Regression?
Not always obvious which type of regression to use
Consider the lobster catch (in millions of lbs.) in the last 30 some years
Enter into Data Matrix
Year
1970
1975
1980
1985
1990
1995
2000 t 5 10 15 20 25 30 35
Lobster 17 19 22 27 36 56

4. Viewing the Data Points
Specify the plot F2,
X's from C1, Y's from C2
View the graph
Check Y= screen, use Zoom-Data

5. Which Regression? The graph could suggest different modeling functions
To find a modeling function which includes the third point makes us think of a polynomial function
To let that point be off the modeling line, it could be a power function or an exponential

6. Try Different Regressions
Try for a quadratic function
Try for power function

7. Try Different Regressions
Try for 4th degree polynomial

8. Try Different Regressions
What about exponential regression?

9. Which is Best? Issues Which best fits data?
Which gives best predictions for years of given data?
Which gives best predictions for future?
Might there be one that gives us an idea of what was done in the past (where we have no records)?

10. Other Technology Tools
Excel will also do regression
Plot data as (x,y) ordered pairs
Right click on data series
Choose Add Trend Line

11. Other Technology Tools
Use dialog box to specify regression
Try Others

12. Assignment
Lesson 9.7
Page 431
Exercises 5, 13, 15, 17, 19