Finding the Best Fitting Line

The following applet, named FindLine, allows you to move the regression line vertically (i.e. changing its intercept) and to rotate it (i.e. changing its slope). The data in the applet are taken from McClelland’s original applet, and show the scores on a Statistical Knowledge Quiz (SKQ) before and after students have taken his statistics course.

Drag the blue square to move the line up and down. Drag anywhere else on the line to change the slope. Clicking anywhere in the graph causes the line to jump so that it goes through the point clicked.

Adjust the line until you think that it is a “best fit.” I happen to know that the best fitting line has an intercept of 10.9, and a slope of 0.42. How does the line you fit compare to that?
By clicking on the icon labeled “My Data,” you can enter your own data. Enter the data on alcohol and tobacco use from Table 9.3 in Chapter 9, and see the results. Gary, How big a job would it be to allow for this?

Does the applet calculate min and max for each axis from the data given as parameters, or can I just supply different values for the parameters and have everything come out right? I would like to display a set of data from the book as well as your SKQ data.

Comments to: Gary.McClelland@Colorado.e du

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