
Displaying the equation
▲
Press to return to Symbolic view.
Note the expression in the Fit1 eld. It shows that the slope (m) of the regression line is 425.875 and the
y-intercept (b) is 376.25.
Predicting values
Let’s now predict the sales gure if advertising were to go up to 6 minutes.
1.
Press to return to Plot view.
The trace option is active by default. This option will move the cursor from data point to data point as
you press
or As you move from data point to data point, the corresponding x- and y-values
appear at the bottom of the screen. In this example, the x-axis represents minutes of advertising and
the y-axis represents sales.
However, there is no data point for 6 minutes. Thus we cannot move the cursor to x = 6. Instead, we need
to predict what y will be when x = 6, based on the data we do have. To do that, we need to trace the
regression curve, not the data points we have.
Getting started with the Statistics 2Var app 251
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