ENTERING DATA & FINDING BEST FIT LINES

 

Suppose you have the following data on the United States’ Federal Debt:

 

Year

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

Federal Debt (millions of $)

3.599

4.002

4.351

4.644

4.921

5.182

5.370

5.479

5.606

5.629

5.770

 

 

ENTERING AND ALIGNING DATA

 

1.) First, get your calculator into the right mode:

            STAT, then EDIT, then 1:EDIT

 

2.) Now, clear lists L1 and L2:  (if they are already clear, you can skip this step)

- with the “up arrow”, move the cursor to L1

- CLEAR, then ENTER

- repeat for L2

 

3.) Enter data into L1:

            1991 ENTER

            1992 ENTER….

           

            2001 ENTER

 

4.) Enter data into L2:

            3.599 ENTER

            4.002 ENTER….

           

            5.770 ENTER

 

5.) If you’d like to align the data with 1990 as your base year:

- with the “up arrow”, move the cursor to L1

- 2nd, then L

- “-“ then 1990

-         ENTER

 

6.) Back to home screen: 2nd QUIT

 

 

 

 

 

 

 

 

 

 

Now, suppose you want a scatter plot:

 

1.) Make sure all plots in Y= list are turned off or cleared.

 

2.) Set the plot up:

- 2nd, then STAT PLOT

- 1:PLOT1, then ENTER

- ON, then ENTER

- Type: select scatter plot

- Xlist: L­1, Ylist: L2

- Mark: select box

 

3.) To get a plot: ZOOM, then 9:ZoomStat

 

To get a “Best Fit” line:

 

1.) STAT, then CALC

 

2.) 4:LinReg, then ENTER

 

3.) VARS, then Y-VARS

 

4.) 1:FUNCTION

 

5.) 1:Y1, then ENTER

      NOTE: This should take you back to the home screen, with a command

that looks like: LinReg(ax+b) Y1

 

7.) ENTER

 

8.) Check to see if the equation is in the Y= list, by pressing Y=

 

9.) To graph, just hit GRAPH

 

10.) To plug x-values into the new function:

- VARS, then Y-VARS

- 1:FUNCTION

- 1:Y1, then ENTER

- open up left parentheses “(“, key in your number, then right parentheses “)”

- ENTER