Exercise 16: Understanding Independent Samples t-Test

• 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.
• What are the means and standard deviations (SDs) for age for the Buzzy intervention and control groups? What statistical analysis is … to determine the difference in means for age for the two groups? Was this an appropriate analysis technique? Provide a rationale for your answer.
• What are the t value and p value for age? What do these results mean?
• assumptions for conducting the independent samples t-test?
• Are the groups in this study independent or dependent? Provide a rationale for your answer.
• 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 … in this study? Provide a rationale for your answer.
• Should a Bonferroni procedure … conducted in this study? Provide a rationale for your answer.
• What variable has a result of t = −6.135, p = 0.000? What does this result mean?
• In your opinion, is it an expected or unexpected finding that both t values on Table 2 were found to … statistically significant. Provide a rationale for your answer.
• Describe one potential clinical benefit for pediatric patients to receive the Buzzy interven¬tion that combined cold and vibration during IV insertion.

Exercise 17: Understanding Paired or Dependent Samples t-Test

• What are the assumptions for conducting a paired or dependent samples t-test in a study? Which of these assumptions do you think were … by the Lindseth et al. (2014) study?
• In the introduction, Lindseth et al. (2014) described a “2-week washout between diets.” What does this mean? Why is this important?
• What is the paired t-test value for mood (irritability) between the participants’ consump¬tion of high- versus low-aspartame diets? Is the result statistically significant? Provide a rationale for your answer.
• 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.
• 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 ratio¬nale for your answer.
• Discuss why the larger t values are more likely to … statistically significant.
• Discuss the meaning of the results regarding depression for this study. What is the clinical importance of this result?
• What is the smallest, paired t-test value in Table 2? Why do you think the smaller t values are not statistically significant?
• Discuss the statistical and clinical importance of these study results about the consump¬tion of aspartame. Document your answer with a relevant source.
• Are these study findings related to the consumption of high- and low-aspartame diets ready for implementation in practice?

Exercise 31: Calculating t-tests for Independent Samples

• Do the example data meet the assumptions for the independent samples t-test? Provide a rationale for your answer.
• 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?
• What are the means for two group’s wages … ?
• What is the independent samples t-test value?
• Is the t-test significant at a = 0.05? Specify how you arrived at your answer.
• 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?
• Which group earned the most money post-treatment?
• Write your interpretation of the results, as you would in an APA-formatted journal.
• What do the results indicate regarding the impact of the supported employment voca¬tional rehabilitation on wages earned?
• Was the sample size adequate to detect significant differences between the two groups in this example?

Exercise 32: Calculating t-tests for Paired (Dependent) Samples

• Do the data meet the assumptions for the paired samples t-test? Provide a rationale for your
• 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?
• What are the means for the baseline and post-treatment affective distress scores, respectively?
• What is the … samples t-test value?
• Is the t-test significant at α = 0.05? Specify how you arrived at your answer.
• 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?
• On average, did the affective distress scores improve or deteriorate over time? Provide a rationale for your answer.
• Write your interpretation of the results as you would in an APA-formatted journal.
• What do the results indicate regarding the impact of the rehabilitation on emotional dis¬tress levels?
• What are the weaknesses of the design in this example?