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.
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.
|
Scores in 7minute-screen (Y) |
Scores in Cognitive series (X) |
|
0 |
11 |
|
4 |
19 |
|
6 |
22 |
|
8 |
20 |
|
5 |
14 |
|
4 |
13 |
A)
Calculate the Pearson
B)
If the researchers centered the variable of 7-minute screen (i.e., every score in this variable minus its
C)
Is the correlation statistically significant? Use a two-tailed test with α = .05.
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