This calculator starts out with 20 randomly chosen X, Y pairs with values between 1 and 10. Try the following manipulations on these random data to see what happens to the correlation coefficient.

- Click the "compute" button to calculate a Pearson correlation coefficient (r) from random values.
- Is the correlation coefficient near zero? A correlation calculated from random numbers will often be close to zero, but not always.
- Verbally describe this correlation as none (near zero), weak (about +/- .3), medium, or strong (near +1.0 or -1.0).
- Try making all of the X values similar to the corresponding Y values. What happens to the correlation coefficent? Example: The pair 2,9 becomes 8,9.
- Try making the X, Y values dissimilar by adding 10 to each X value. For example, 3,5 becomes 13,5.
- What happens when the small X values are accompanied by a large Y value? Also, make large X values have a small Y. Examples: 2,10 and 10,2.

To start over, click on the "try again" button.

*** Waiting for results ***

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