# Correlation questions

1. For the following scores,

X Y

3 6

6 1

3 4

3 3

5 1

a) Find the regression equation for predicting Y from X

b) Calculate the predicted Y value for each X

2. For the following scores

X Y

1 6

4 1

1 4

1 3

3 1

a) Compute the Pearson correlation

3. Identifying individuals with a high risk of Alzheimer's disease usually involves a long series of cognitive tests. However, researcher have developed a 7-Minute Scree, 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.

Patient 7-Minute Screen Cognitive Series

A 3 11

B 8 19

C 10 22

D 8 20

E 4 14

F 7 13

G 4 9

H 5 20

I 14 25

a) Compute the Pearson correlation to measure the degree of relationship between the two scores.

b) Is the correlation statistically significant? Use a two-tailed test with an alpha=.01

c) What percentage of variance for the cognitive scores is predicted from the 7-Minute Screen scores? (Compute the value of r2 )

#### Solution Summary

The solution provides detailed explanation how to find the correlation coefficient and figure out the regression equation.