The following data are indexed prices of gold and copper over a 10-year period. Assume that the indexed values constitute a random sample from the population of possible values. Test for the existence of a linear correlation between the indexed prices of the two metals.

Gold: 76, 62, 70, 59, 52, 53, 53, 56, 57, 56

Copper: 80, 68, 73, 63, 65, 68, 65, 63, 65, 66

Also, state one limitation of the data set.