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.
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 Coefficient for these data.
r =
Note: For all the calculations, if it is a decimal number with two or more than two places, leave only two decimal places after the decimal point and do not round.
If it is a negative correlation, please do not forget to include the negative sign.
B) The correlation is
Medium and negative
Large and negative
Large and positive
Medium and positive
C) The null hypothesis for a two-tailed test is
The correlation between the scores on the 7-minute screen test and the scores on the cognitive series is significant
The correlation between the scores on the 7-minute screen test and the scores on the cognitive series is not significant
The correlation between the scores on the 7-minute screen test and the scores on the cognitive series is less than zero
The correlation between the scores on the 7-minute screen test and the scores on the cognitive series is different from zero
D) The alternative hypothesis in symbols for a two-tailed test is
H1: ρ = 0
H1: ρ ≠ 0
H1: r = 0
H1: r ≠ 0
E) If we use a two-tailed test with α = .01, the critical r values are:
±0.666
±0.582
±0.798
±0.750
F) Your decision is:
Reject the null hypothesis and conclude that there is a significant correlation between the scores on the 7-minute screen test and the scores on the cognitive series
Fail to reject the null hypothesis and conclude that there is a significant correlation between the scores on the 7-minute screen test and the scores on the cognitive series
Reject the null hypothesis and conclude that there is no significant correlation between the scores on the 7-minute screen test and the scores on the cognitive series
Fail to reject the null hypothesis and conclude that there is no significant correlation between the scores on the 7-minute screen test and the scores on the cognitive series
G) Report the results in APA
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