Correlation by eye

The applet below allows one to guess the sample correlation, r, for a data set. When the applet loads, a data set consisting of 20 points is displayed. Points can be added to the plot by clicking the mouse. Points on the plot can be removed by clicking on the point and then dragging the point into the trash can. All of the points on the plot can be removed by simply clicking inside the trash can. Enter your guess for r in the Guess field, and then click the Show r! button to see if you are within 0.1 of the true value. Click the New data button to generate a new data set.
  • Try to guess the value of r for 10 different data sets.
  • Try to create a data set with a value of r that is approximately 0.9. Try to create a data set with a value of r that is near 0.