1. Do the example data meet the assumptions for the paired samples t -test? Provide a rationale for your answer.
Yes. This example data meets the assumption for paired t-test. This is true since the sample elements (variables) have been obtained from a solitary collection of participants with like characteristics for baseline and post-treatment probing.
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2. If calculating by hand, draw the frequency distributions of the two variables. What are the shapes of the distributions? If using SPSS, what are the results of the Shapiro-Wilk tests of normality for the two variables?
Tests of Normality |
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Kolmogorov-Smirnov a |
Shapiro-Wilk |
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Statistic |
df |
Sig. |
Statistic |
df |
Sig. |
|
Baseline Affective |
.134 |
10 |
.200 * |
.953 |
10 |
.705 |
Post-treatment Affective |
.235 |
10 |
.124 |
.912 |
10 |
.292 |
*. This is a lower bound of the true significance. | ||||||
a. Lilliefors Significance Correction |
The study gives Shapiro-Wilk p-value of 0.705 for the baseline and 0.292 for the post treatment.
3. What are the means for the baseline and posttreatment affective distress scores, respectively?
Paired Samples Statistics |
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Mean |
N |
Std. Deviation |
Std. Error Mean |
||
Pair 1 | Baseline Affective |
3.03 |
10 |
1.664 |
.526 |
Post-treatment Affective |
2.040 |
10 |
.9834 |
.3110 |
The baseline effective distress had a mean of 3.030 while Post Treatment Distress had a mean of 2.040.
4. What is the paired samples t -test value?
Paired Samples Correlations |
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N |
Correlation |
Sig. |
||
Pair 1 | Baseline Affective & Post-treatment Affective |
10 |
.777 |
.008 |
Paired Samples Test |
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Paired Differences |
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Mean |
Std. Deviation |
Std. Error Mean |
95% Confidence Interval of the Difference |
||
Lower |
|||||
Pair 1 | Baseline Affective - Post-treatment Affective |
.9900 |
1.0929 |
.3456 |
.2082 |
Paired Samples Test |
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Paired Differences |
t |
df |
Sig. (2-tailed) |
|||||
95% Confidence Interval of the Difference |
||||||||
Upper |
||||||||
Pair 1 | Baseline Affective - Post-treatment Affective |
1.7718 |
2.865 |
9 |
.019 |
The paired sample t-test value from the SPSS output is 2.865
5. Is the t -test significant at α = 0.05? Specify how you arrived at your answer.
The t-test is significant at α=0.05. We reached this conclusion by using the computed p-value of 0.019, since this value is lower than α=0.05.
6. If using SPSS, what is the exact likelihood of obtaining a t- test value at least as extreme as or as close to the one that was actually observed, assuming that the null hypothesis is true?
The precise probability of getting a t-test value that is as extreme or as near to the one that was truly observed if we take on the null hypothesis to be true will be greater than 0.099% but less than 0.1%.
7. On average, did the affective distress scores improve or deteriorate over time? Provide a rationale for your answer.
Typically, the effective score worsened but eventually became stable. The stable values in the affective distress are denoted by a constant Q-Q line fore the baseline and post-treatment affective distress.
8. Write your interpretation of the results as you would in an APA-formatted journal.
The paired sample t-test computed from the baseline affective distress and post-treatment affective distress disclosed worsening of distress score over time, t (9) =2.865, p>0.001; means for two tests are 3.03 and 2.04. This shows that the method of treatment is significant and effective for affective distress.
9. What do the results indicate regarding the impact of the rehabilitation on emotional distress levels?
The findings show that rehabilitation reduces emotional distress levels amid patients.
10. What are the weaknesses of the design in this example?
It’s not trivial to determine establish whether the changes in the samples have been caused by the involvement of the program or not. The design doesn’t consider other factors that may have impacted the changes.