First look at the correlation for just those subjects who scores over 100 on Grip Strength. Do this by moving the left-hand bar to the right until the right-most portion of the bar is on 100. This will exclude all scores below 100 on the graph at the bottom of the screen. Look to see how many subjects are incuded on the bottom. It should be 95. Looking at the graph, the relationship between the two measures of strength appears smaller. The correlation is 0.50. This is lower than the correlation of 0.63 found with the whole sample.

Now look at the correlation if only scores above 140 are included. The correlation drops to 0.39.

Now consider the correlation when you exclude the middle portion of the distribution. Move the left bar to 80 and the right bar to 140. Then click the button "Data outside bars." This will include only the date outside the bars on the plot below. Observe the correlation when only these values are considered.

Choose another dataset such as SAT and see if the same results occur.