# Solutions to Exercise 16, 17, 31, and 32

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Solutions for Exercise 16 Questions

1. What do degrees of freedom (df) mean? Canbulat et al. (2015) did not provide the dfs in their study. Why is it important to know the df for a t ratio? Using the df formula, calculate the df for this study.

2. What are the means and standard deviations (SDs) for age for the Buzzy intervention and control groups? What statistical analysis is conducted to determine the difference in means for age for the two groups? Was this an appropriate analysis technique? Provide a rationale for your answer.

3. What are the t value and p value for age? What do these results mean?

4. What are the assumptions for conducting the independent samples t-test?

5. Are the groups in this study independent or dependent? Provide a rationale for your answer.

6. What is the null hypothesis for procedural self-reported pain measured with the Wong Baker Faces Scale (WBFS) for the two groups? Was this null hypothesis accepted or rejected in this study? Provide a rationale for your answer.

7. Should a Bonferroni procedure be conducted in this study? Provide a rationale for your answer.

8. What variable has a result of t = −6.135, p = 0.000? What does the result mean?

9. In your opinion, is it an expected or unexpected finding that both t values on Table 2 were found to be statistically significant. Provide a rationale for your answer.

10. Describe one potential clinical benefit for pediatric patients to receive the Buzzy intervention that combined cold and vibration during IV insertion.

Solutions to Exercise 17 Questions

1. What are the assumptions for conducting a paired or dependent samples t-test in a study? Which of these assumptions do you think were met by the Lindseth et al. (2014) study?

2. In the introduction, Lindseth et al. (2014) described a “2-week washout between diets.” What does this mean? Why is this important?

3. What is the paired t-test value for mood (irritability) between the participants’ consumption of high- versus low-aspartame diets? Is this result statistically significant? Provide a rationale for your answer.

4. State the null hypothesis for mood (irritability) that was tested in this study. Was this hypothesis accepted or rejected? Provide a rationale for your answer.

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5. Which t value in Table 2 represents the greatest relative or standardized difference between the high- and low-aspartame diets? Is this t value statistically significant? Provide a rationale for your answer.

6. Discuss why the larger t values are more likely to be statistically significant.

7. Discuss the meaning of the results regarding depression for this study. What is the clinical importance of this result?

8. What is the smallest, paired t-test value in Table 2? Why do you think the smaller t values are not statistically significant?

9. Discuss the clinical importance of these study results about the consumption of aspartame. Document your answer with a relevant source.

10. Are these study findings related to the consumption of high- and low-aspartame diets ready for implementation in practice? Provide a rationale for your answer.

Solutions to Exercise 31 Questions

1. Do the example data meet the assumptions for the independent samples t-test? Provide a rationale for your answer.

2. If calculating by hand, draw the frequency distributions of the dependent variable, wages earned. What is the shape of the distribution? If using SPSS, what is the result of the Shapiro-Wilk test of normality for the dependent variable?

3. What are the means for two group’s wages earned?

4. What is the independent samples t-test value?

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5. Is the t-test significant at a = 0.05? Specify how you arrived at your answer.

6. If using SPSS, what is the exact likelihood of obtaining a t-test value at least as extreme or as close to the one that was actually observed, assuming that the null hypothesis is true?

7. Which group earned the most money post-treatment?

8. Write your interpretation of the results as you would in an APA-formatted journal.

9. What do the results indicate regarding the impact of the supported employment vocational rehabilitation on wages earned?

10. Was the sample size adequate to detect significant differences between the two groups in this example? Provide a rationale for your answer.

Solutions to Exercise 32 Questions

1. Do the example data meet the assumptions for the paired samples t-test? Provide a rationale for your answer.

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?

3. What are the means for the baseline and posttreatment affective distress scores, respectively?

4. What is the paired samples t-test value?

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5. Is the t-test significant at α = 0.05? Specify how you arrived at your answer.

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?

7. On average, did the affective distress scores improve or deteriorate over time? Provide a rationale for your answer.

8. Write your interpretation of the results as you would in an APA-formatted journal.

9. What do the results indicate regarding the impact of the rehabilitation on emotional distress levels?

10. What are the weaknesses of the design in this example?