1. Using TI graphing calculators
Regression tutorial
Using TI graphing calculators

2. The regression feature of a graphing calculator can be used to find mathematical models for sets of data.
Suppose we want to find a linear equation to model or “fit” the data in this table: 8 5 3 1 y 4 2 x

3. To enter the data Press STAT Select EDIT by pressing ENTER
If you already see data listed in the L columns, you must clear it. Click here for directions to clear previous data.

4. 8 5 3 1 y 4 2 x
To enter the data
Enter the values of the independent variable in the first column, pressing ENTER after each one. This should be L1

5. 8 5 3 1 y 4 2 x
To enter the data
Use the arrow keys to move the cursor to the second column, L2
L1 and L2 are called lists.
Enter the values of the dependent variable in the second column beside the corresponding numbers in the first column, pressing ENTER after each one.

6. Caution!
You must have the same number of entries in each column or you will get a DIM MISMATCH error

7. To plot the data points
Clear any functions entered in the Y= list or they will be graphed along with your data points.
Press STAT PLOT (2nd Y=)
Press ENTER
2nd MODE(to leave that screen)

8. To plot the data points
Move the cursor to highlight ON and press ENTER
If any settings differ from the ones show on the right, correct them by using your arrow keys

9. To plot the data points
Choose a window to fit the values in your data lists.
You can also press ZOOM,
#9(STAT)
Press GRAPH

10. To calculate a regression equation
Press STAT
Move to CALC

11. To calculate a regression equation
Choose the type of regression you want for your equation. LINREG is for a linear function, EXPREG is exponential, etc.
In this example, use the arrow keys to highlight LINREG
Press ENTER to select

12. To calculate a regression equation
Press ENTER again
The calculated numbers for the regression are on the home screen
The regression equation is
y = 2.3x – 1.5

13. To graph the regression equation You can type in the equation in your Y= menu OR pull it from memory as described below:
Follow the procedure to calculate a regression equation
Press Y=
Press VARS
Press #5
Move Cursor to EQ
Select #1: RegEQ

14. To graph the regression equation
Press ENTER
This brings the regression equation to Y1

15. To graph the regression equation
Press GRAPH and you will see the data points as well as the graph of the regression equation.

16. To clear data in the stats lists
Use the arrow keys to move the cursor on top of the L1 column and press CLEAR (not DELETE).
Repeat for L2.
Do NOT press DELETE. This will delete the whole column, not just the data. (click here to return to tutorial)

17. Reminder
Be sure to go back and turn the STAT PLOT off when you are ready to go back to “regular” function graphing.
Press 2nd STAT PLOT, press ENTER
Move over to highlight OFF and press ENTER again.