Problem:
Given the following table:

 Year: DJ Average 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 824 972 882 1027 1252 1198 1537 1927 2015 2144
[Extracted from the Chance site.]

find and graph the least squares regression line.

Solution:
Using the TI-85 graphing calculator:

[Press here to see animation again!]

1. Press the STAT key and then pick  EDIT  by pressing the F2 key.
2. You can change the names for the list of values which you will be entering but it is not necessary. Press the ENTER key twice if do not change the names.
3. To clear out previous data, pick  CLRxy  by pressing the F5 key.
4. At the prompt  x1= , type in the first year as the first x-value: 1980 and press the ENTER key.
5. At the prompt  y1= , type in the first DJ Average as the first y-value: 824 and press the ENTER key.
6. Keep repeating this to enter all ten pairs of numbers. After you have entered the tenth pair, press the EXIT key.
7. Pick  CALC  by pressing the F1 key.
8. Press the ENTER key twice and you will be given the opportunity to choose a number of options including  LINR  choose this option by pressing the F2 key.
9. You will see the following screen:

This indicates that the equation of the least squares line is:

y = -309912.072727 + 156.8606061 x

10. Press the EXIT key followed by the DRAW key.
11. If some previous graph appears on the screen then
• pick  CLDRW  by pressing the F5 key.
• If the previous graph still appears then press the GRAPH key and choose  y(x)=  by pressing the F1 key.
• Press F4 key several times until no function appears on the screen.
• Proceed with changing the bounds of the viewing screen as outlined in the next item.
12. Most probably you will need to change to the bounds of the viewing screen to see all of the data points. To do this,
• Press the GRAPH key and then choose  RANGE  by pressing the F2 key.
• Enter the following data:

• You will then need to press the EXIT key followed by the STAT and DRAW keys to return where you were.
13. Pick  SCAT  by pressing the F2 key to see the collection of data points:

14. Pick  DRREG  by pressing the F4 key to draw the graph of the least squares line: