Playing with Regression Lines

In tonight's homework you're working through the mechanics of generating a linear equation for a given set of data (points in the cartesian plane). It's easy to loose sight of what this all means or what it is exactly that we are supposed to be doing.

I'd like you to take a look at this online tool. It may take a moment or two to fully load in your browser. When it does you'll see a blank, white graph on the left and a horizontal line on a grey graph on the right. Clicking on the white graph will put a blue point at that spot. Add as many as you like. You'll also see a red line whose position changes as you add more points. Basically, this applet is drawing the "line of best fit" for the (random?) set of points you specify.

Play with it for a bit try to:

• get a line that has NONE of the points you create on it


• get a horizontal line that has none of the points on it


• get a vertical line using as few or as many points as you like

We'll talk about your results in tomorrow's class. We'll also talk about what we're looking at in the grey graph.

Have Fun!!