Let's begin by plotting the values using our graphing calculator. Let's treat 1900 as x=0 in our model.
x
y
65
630
80
1300
95
1950
105
2650
Push STAT, choose Edit, and enter your values.
Once the values have been entered, we can plot them by pushing 2nd and Y= and choosing one of the plots in the list. Make sure you turn the plot ON, choose scatterplot as the type, and use L1 and L2 as XList and YList. Finally, you can pick whatever mark you want.
By pushing GRAPH the calculator will plot the dataset. A standard viewing window might not show the data points, so we can change it if necessary.
By pressing STAT you can find the linear regression under the CALC menu. If we choose LinReg the calculator performs a linear regression test. Further down the list we can find ExpReg, which performs an exponential regression.
Which Model Is Best?
To determine which model is best, we will plot the results we got and examine how they fit the data.
Both graphs fit the data set very well. However, if we look at the r^2 value, we see that it is 1 for the cubic regression. This means it fits the data set perfectly. Therefore, we will choose the cubic model as the better fit.
