Identifying individuals with a high risk of Alzheimer’s disease usually involves a long series of cognitive tests. However, researchers have developed a 7-Minute Screen, which is a quick and easy way...

Identifying individuals with a high risk of Alzheimer’s disease usually involves a long series of cognitive tests. However, researchers have developed a 7-Minute Screen, which is a quick and easy way to accomplish the same goal. The question is whether the 7-Minute Screen is as effective as the complete series of tests. To address this question, Ijuin et al. (2008) administered both tests to a group of patients and compared the results. The following data represent results similar to those obtained in the study.

A)

Calculate the Pearson correlation for these data.

B)

If the researchers centered the variable of 7-minute screen (i.e., every score in this variable minus its Mean), what would be the new value of correlation?

C)

Is the correlation statistically significant? Use a two-tailed test with α = .05.