Statistics for Nursing Research: A Workbook for Evidence-Based Practice, 2nd Edition

Exercise 16: Understanding Independent Samples t-test

Questions to Be Graded

1. What do degrees of freedom (df) mean?

A. It is a mathematical concept that describes the freedom of a particular score’s value independent of the other existing scores’ values and the sum of the scores.

B. It is a mathematical concept that describes the freedom of a particular score’s value to vary on the other existing scores’ values and the sum of the scores.

Answer: Choose an item.

Canbulat et?al. (2015) did not provide the dfs in their study. Why is it important to know the df for a t ratio?

A. The df for t-tests allows us to look up t ratios on a statistical table that includes a distribution of the critical values of t to determine the significance of the t values obtained in a study.

B. The df for t-tests allows us to look up t ratios on a statistical table that includes a distribution of the critical values of t to determine the sign (positive or negative) of the t values obtained in a study.

Answer: Choose an item.

Using the df formula, calculate the df for this study.

A. 87

B. 88

C. 174

D. 176

Answer: Choose an item.

2. What are the means and standard deviations (SDs) for age for the Buzzy intervention and control groups?

Mean±SD for the Buzzy experimental group and Mean±SD for the control group were:

A. 8.05±1.51; 8.31±1.69.

B. 8.15±1.51; 8.41±1.69.

C. 8.05±1.51; 8.51±1.69.

D. 8.25±1.51; 8.61±1.69.

Answer: Choose an item.

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.

A. Independent sample t-test. Appropriate.

B. Independent sample t-test. Not appropriate.

C. Paired sample t-test. Appropriate.

D. Paired sample t-test. Not appropriate.

Answer: Choose an item.

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

A. The t=-3.459 and p value=0.005. A significant difference in age between the two treatment groups.

B. The t=-2.489 and p value=0.013. A significant difference in age between the two treatment groups.

C. The t=-1.489 and p value=0.136. No significant difference in age between the two treatment groups.

Answer: Choose an item.

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

A. The variable is normally distributed.

B. The dependent variable(s) is (are) measured at the interval or ratio levels.

C. The two groups have equal variance.

D. All observations within each group are independent

E. All of the above.

Answer: Choose an item.

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

A. The groups in this study are independent since the study participants were randomly assigned to either the intervention group or the control group.

B. The groups in this study are not independent since the study participants were not randomly assigned to either the intervention group or the control group.

Answer: Choose an item.

6. What is the null hypothesis for procedural self-reported pain measured with the Wong Baker Faces Scale (WBFS) for the two groups?

A. There is no difference in procedural self-reported pain with the WBFS between the Buzzy intervention and control groups of school age children.

B. There is a difference in procedural self-reported pain with the WBFS between the Buzzy intervention and control groups of school age children.

Answer: Choose an item.

Was this null hypothesis accepted or rejected in this study? Provide a rationale for your answer.

A. Accepted (or not rejected).

B. Rejected.

Answer: Choose an item.

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

A. Yes, in order to control Type I error, because there were multiple t-tests performed.

B. No, because no multiple tests were performed.

Answer: Choose an item.

8. What variable has a result of t = ?6.135, p = 0.000?

A. Procedural self-reported pain with WBFS

B. Procedural self-reported pain with VAS

C. Procedural anxiety level

Answer: Choose an item.

What does the result mean?

A. There is a significant difference between the two groups in the variable of interest.

B. There is no significant difference between the two groups in the variable of interest.

Answer: Choose an item.

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.

A. It would be expected

B. It would be unexpected

that if both WBFS and VAS are reliable and valid methods of measuring pain that the results would be consistent and in this case statistically significant for both measurement methods.

Answer: Choose an item.

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

A. Decreased pain and anxiety levels.

B. Nonpharmacological

C. fast-acting, inexpensive, and easy to use

D. A & B

E. A & B & C

Answer: Choose an item.

Statistics for Nursing Research: A Workbook for Evidence-Based Practice, 2nd Edition

Exercise 17: Understanding Paired or Dependent Samples t-test

1. What are the assumptions for conducting a paired or dependent samples t-test in a study?

A. The distribution of scores is normal or approximately normal

B. The dependent variable is measured at interval or ratio levels

C. Repeated measures from one group of subjects where they serve as their own control

D. The differences between the paired scores are independent

E. The repeated measures for one subject are independent

F. A to D

G. A to E

Answer: Choose an item.

Which of these assumptions do you think were met by the Lindseth et?al. (2014) study?

A. A to D in the previous sub-question.

B. A to E in in the previous sub-question.

Answer: Choose an item.

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

A. A period to clear their bodies of the level of aspartame consumed over the previous 8 days. It is important because the effects of the first invention can be reduced or removed so that they do not affect the outcome of the second intervention.

B. A period to wait for the effect of aspartame consumed over the previous 8 days. It is important because the effects of the first invention can be considered and evaluated again for the second intervention.

Answer: Choose an item.

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.

A. 3.2. Significant, because p<>.05.

B. 3.2. Not significant, because p is not <>.05.

C. 3.4. Significant, because p<>.05.

D. 3.4. Not significant, because p is not <>.05.

Answer: Choose an item.

4. State the null hypothesis for mood (irritability) that was tested in this study

A. There is a difference in mood (irritability) for the participants’ after consumption of the low- versus high-aspartame diets.

B. There is no difference in mood (irritability) for the participants’ after consumption of the low- versus high-aspartame diets.

Answer: Choose an item.

Was this hypothesis accepted or rejected? Provide a rationale for your answer.

A. Accepted, because p<>.05 (significant result)

B. Accepted, because p>=0.05

C. Rejected, because p<>.05 (significant result)

D. Rejected, because p>=0.05

Answer: Choose an item.

5. Which t value in Table 2 represents the greatest relative or standardized difference between the high- and low-aspartame diets?

t value for spatial orientation

B. t value for working memory

C. t value for mood

D. t value for depression

Answer: Choose an item.

Is this t value statistically significant? Provide a rationale for your answer.

A. Yes, because it is less than ?=0.05.

B. Yes, because it is greater than ?=0.05.

C. No, because it is less than ?=0.05.

D. No, because it is greater than ?=0.05.

Answer: Choose an item.

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

A. The larger the differences in the variable, the larger the t value.

B. The smaller the difference in the variable, the larger the t value.

Answer: Choose an item.

7. Discuss the meaning of the results regarding depression for this study.

A. Depression is significantly higher after consuming a high-aspartame diet than after consuming a lower aspartame diet.

B. Depression is not significantly higher after consuming a high-aspartame diet than after consuming a lower aspartame diet.

Answer: Choose an item.

What is the clinical importance of this result?

A. More Americans are consuming diet drinks and food that often contain aspartame.

The more aspartame they consume, the more likely they are to experience depression. Nurses need to know there is a link of aspartame consumption to depression and educate their patients.

B. More Americans are consuming diet drinks and food that often contain aspartame.

The amount of aspartame they consume has no association with depression. Nurses need to know there is no link of aspartame consumption to depression and no need to waste time for educating their patients.

Answer: Choose an item.

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

A. 1.2. Relative small difference.

B. 1.2. Relative large difference.

C. 1.5. Relative small difference.

D. 1.5. Relative large difference.

Answer: Choose an item.

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

Answer: Choose an item.

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.

A. The findings are not ready for implementation because the sample size is not large enough and safety is not well understood. However, they do have implications for practice because of possible health outcomes after consuming higher amount of aspartame.

B. The findings are ready for implementation because the sample size is large enough and safety is well understood. The findings also have implications for practice because of possible health outcomes after consuming higher amount of aspartame.

Answer: Choose an item.

Please do not add or delete a row or column for the following grading table. If you have a problem with the drop-down lists, then you can enter your answers in the second column. If you use the drop-down lists, the instructor will update your answers in the table. Thanks

Question

Your answer

Correct answer

Possible points

Your points

16. 1

1.5

1

1.5

1

1

2

2

2

2

3

4

4

4

5

4

6

2

6

2

7

4

8

2

8

2

9

4

10

4

17.1

2

1

2

2

4

3

4

4

2

4

2

5

2

5

2

6

4

7

2

7

2

8

4

9

4

10

4

Total

80