This material was adapted from:

Solving Linear Regression Problems Using the TI 83 Graphing Calculator
An AskERIC Lesson Plan

Supose you have some data:

The goal of this tutorial is to help you...

...make a scatterplot of the table above on your graphing calculator.

...graph the Linear Regression Equation in the form y = mx + b

Do the following...

1. The TI-89 does things differently than the TI-83+. The TI-89 can set any variable to a data matrix and so the first step is to create a new data matrix. Tap the APPS Menu and navigate to the Data/Matrix editor item. (n.b. with the new operating system this may appear as an icon rather than a menu list)
2. Choose a new from the pop-up list and designate the type as data, you may leave the default folder where it is and giev the new data matrix a name, say 'aster'.
3. Tap ENTER, You will then see a spreadsheet of columns designated as c1, c2, etc, with row numbers down the left side. Enter the distance into the first cell and tap ENTER the next cell below has now been selected. Enter the rest of the distance column. When you reach the end use the arrow keys to move the selection to the first cell of the c2 column. Enter all the periods as well.
4. To plot these data points on a graph, you can simply tap the F2 key. A menu of all the stat plots will be listed. You can store up to 9 different stat plots which the calculator will "remember" from now on. Choose a plot (pick Plot 1 if it isn't already set up) and tap the F1 key.
   1. Make sure the plot type is Scatter and select Box as the Mark.
   2. Move the cursor down to the x entry and type "c1" (remember to turn off the alpha designator when trying to type the numeral 1).
   3. Move down to the y entry and type "c2"
   4. Leave every thing else untouched.
5. Tap ENTER, twice and tap the GRAPH key (above the F3 key).
6. You should see a graph full of the points but if you don't you may have to re-scale the axes. Tap the F2 key and choose the 9th item by tapping the 9 key. The graph should rescale to include all the points.Now graph the scatterplot by hitting GRAPH.
   If you don't see your scatterplot, here are a couple of possible reasons why:
   1. If your calculator gives a dialog box with ERROR: Dimension Mismatch, check your 2 lists to see if you have the same number of elements in each list (you may not). Do this tapping ESC and 2nd APPS.
   2. If nothing appears on your graph, you may not have turned the plot on. Tap F2 and make sure there is a check in front of the Plot you set up for charting.
7. To fit the data to a linear regression tap the 2nd APPS and tap the F5 key. You should see a menu similar to the plot set up screen.
   1. Choose LinReg from the pop-up meny (tap the right arrow key)
   2. Move the cursor down to the x entry and type "c1" (remember to turn off the alpha designator when trying to type the numeral 1).
   3. Move down to the y entry and type "c2"
   4. Choose y1(x) from the pop-up menu to store the resulting fit.
   5. Leave everything else untouched.
8. Tap ENTER and you will see a display indicating the best fit. You should see:
   

   a	0.019564
   b	-0.396275
   corr	.512869
   R2	.263034

9. Tap ENTER to make the dialog go away. The equation is already entered into the function generator so to see the fit you need only tap the GRAPH key or 2nd APPS to swap screens. The graph will now show both the data and the best fit line.