Another method for finding a best-fit model is using graphing technology – either a graphing calculator or available computer software/applets. We will look at both technologies!

First with the graphing calculator . . .

Below is a table with data of values showing the speed of the wind and the pressure caused by the wind against the side of a skyscraper building. As you probably expect . . . the greater the wind speed, the greater the pressure against the side of the building.
Wind Speed
(in miles per hour)		 Pressure
(in lbs of force per square foot)
10 1.0
20 1.6
30 2.8
40 4.3
50 5.9
60 8.1
70 11.0
80 14.0

First, enter the data into L1 and L2 on your calculator and create a scatterplot of your data. Be sure to set an appropriate viewing window that will enable you to ‘see’ your data.

Next, go to Stat > Calc and choose 5: QuadReg and hit ‘ENTER’ to use the calculator’s regression command to create the model.

Then type L1, L2 ,Y1 after the command to tell that calculator that the x-values you want to model are in L1, the y-values are in L2, and the equation for the model should be stored in Y1.

Next, press ‘ENTER’ to have the calculator find a model to fit the given data.

Finally, press GRAPH to see how closely your quadratic model fits the data in your scatterplot. The Correlation Coefficient tells you how close of a fit the line (or curve) is. The closer the number is to 1, the better the fit you have.

*If you need help entering data into lists in your calculator and performing regression analysis, check out this This activity might not be viewable on your mobile device.online tutorial.