Mean

N

Std. Deviation

Std. Error Mean

Pair 1

Mem1

100.5393

55

9.04178

1.21919

Mem2

97.0727

55

9.17227

1.23679

Paired Samples Test

Paired Differences

t

df

Sig. (2-tailed)

Mean

Std. Deviation

Std. Error Mean

95% Confidence Interval of the Difference

Lower

Upper

Pair 1

Mem1 - Mem2

3.46655

4.51733

.60912

2.24534

4.68775

5.691

54

.000

Q2. Select, perform, and interpret a t test (10 points total)

To examine the aging effect on memory, each subject in the study was tested twice about 10 years apart. The researcher would like to know if memory function changes significantly from the first testing session (Mem1) to the second testing session (Mem2) for all participants. No point is given for this question set (Q2) if the output file for this analysis is not submitted.

Q2A. Selecting the statistical test based on the research question:

Q2A-1. What type of t test should be performed? What is your rationale for selecting this t test?

1 point: .5 for each question

Q2A-2. What is the null hypothesis being tested with this t test?

1 point

Q2B-2. Use the SPSS output to calculate effect size, d. Must show the calculation process.

1 point: deduct .5 if the process is correct but the calculation has errors

Effect size (r) = 0.187 (need to show steps)

Q2B-3. Report the t test result in symbols according to the APA standards, including t statistic with degree of freedom, p value, and effect size d. Present all the items in one single line, separated by commas, and make the symbols italic.

3 points: 1 for t statistic, 1 for p value, 1 for effect size d. Deduct .5 for each statistic if symbol is not italic

Q2B-4. Is the t test significant? Do you reject the null hypothesis?

1 point: .5 for each answer

Q2B-5. Paste the SPSS table showing the means for Mem1 and Mem2 here.

1 point

Q2B-6.Draw a conclusion based on the t test result. (Hint: Is memory significantly different between the first session and the second session? If so, be specific about the direction of such a difference, based on the means in the SPSS table.)

1 point