Regression by Eye

http://www.ruf.rice.edu/%7Elane/stat_sim/reg_by_eye/index.html

 

 

Objective:

• Estimate regression line by eye, and guess the Pearson r-value 

 

When you go to this site, you must click on “begin” to get to the applet.

 

You can draw in the regression line, by clicking and dragging the mouse. When you release the mouse, you’ll see the line and in the box on the right you’ll see the Mean Square Error (MSE) for your line. You can draw in another line to see if you can decrease this. The MSE is the average squared deviations of each data point from the line. Recall that in Least Squares Regression, we minimize the SSE (sum of squared errors), but for simple linear regression, the MSE is just  (SSE/(n-2)). That is, we still want to minimize the MSE.

 

When you check “show regression line,” you’ll see the correct regression line. You can also click on “show minimum MSE” to see that number.

 

Guess the correlation coefficient, r, by choosing one of the options on the right. After you guess, click “show r.”