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Modeling, Functions, and Graphs

Section C.5 Regression

GeoGebra calculator ABC keyboard
Figure C.33. GeoGebra calculator ABC keyboard

Subsection Making a Scatterplot and Finding the Regression Line

We use GeoGebra’s FitLine command to produce a regression line.

Example C.34.

Make a scatterplot for the points \((10,12)\text{,}\) \((11,14)\text{,}\) \((12,14)\text{,}\) \((12,16)\text{,}\) \((14,20)\text{.}\) Then find the equation of the lease-squares regression line and plot it on top of the scatterplot.
We enter each of the five ordered pairs. The output history will show each labeled with a capital letter, such as \(A=(10,12)\text{.}\)
We do a Zoom to fit: right-click on the Graphics View (or click on the gear icon) and select Zoom to fit.
We next enter the FitLine command:
\begin{equation*} \text{fitline}(\{A,B,C,D,E\}) \end{equation*}
using the ABC keyboard shown above for the letters, the 123 keyboard (keyboard image) for the parentheses, and the f(x) keyboard (keyboard image) for the list curly braces {}.
Important: We must enter capital letters for the names of the points--GeoGebra is case-sensitive regarding labels.
Scatterplot and best fit line