Detailed Case,Theory & Numeric Problems-20 Questions - Sample Size, Effect Size, Power Analysis, Hypothesis & Non-Parametric Tests (Ex 13, JUS 302 Ch 9, t test, G*Power, ANOVA, SPSS, etc)

20 questions are attached in four word files. Sample questions are as under:

RESEARCH ARTICLE 2

Source: Voss, J. A., Good, M., Yates, B., Baun, M. M., Thompson, A., & Hertzog, M. (2004). Sedative music reduces anxiety and pain during chair rest after open-heart surgery. Pain, 112 (1–2), 197–203.

Introduction

Voss et al. (2004) conducted a study to determine the “effectiveness of non-pharmacological complementary methods (sedative music and scheduled rest) in reducing anxiety and pain [sensation and distress] during chair rest” (Voss et al., 2004, p. 197) after open-heart surgery. The subjects receiving the treatment of sedative music had significantly less anxiety, pain sensation, and pain distress than those subjects in the scheduled rest and the standard care group. The researchers recommend the use of sedative music as an adjuvant to medication for management of anxiety and pain in postoperative patients. The study only involved patients who had had open-heart surgery, which limits the generalization of the findings. Future research is needed to test the effects of music on the anxiety and pain of different types of patients. In addition, research is needed to determine the optimal length for the music sessions and the effectiveness of repeat music sessions in reducing anxiety and pain.

Relevant Study Results

“An experimental, pretest and posttest three-group design was used for this randomized clinical trial. A convenience sample of 62 patients was obtained from a surgical intensive care unit at a rural midwestern hospital over a period of 6 months in 2002. … The planned sample size of 96 patients (30 per group plus 6 for attrition) was based on power analysis with an estimated medium effect size of 0.33, power 0.80, alpha = 0.05 and repeated measures analysis of variance. However, preliminary analyses after 62 patients were enrolled revealed significant group differences and large effect sizes for anxiety, pain sensation, and pain distress; thus the data collection was concluded” (Voss et al., 2004, p. 198).

1. How large a sample was needed for the Voss et al. (2004) study according to the power analysis? Was this the minimum sample size needed for the study, or did the researchers allow for sample mortality?

2. What was the sample size for the Voss et al. (2004) study? Was this sample size adequate for this study? Provide a rationale for your answer.

3. What effect size was used in conducting the power analysis for this study? What effect size was found during data analysis, and how did this affect the sample size needed for this study?

4. What power was used to conduct the power analysis in the Voss et al. (2004) study? What amount of error exists with this power level? Provide a rationale for your answer.

5. If researchers set the power at 90% to conduct their power analysis, would there be less or more chance of a Type II error than setting the power at 80%? Provide a rationale for your answer.

6. If researchers set the alpha (α) for their study at 0.001 versus 0.05, would they need a smaller or larger sample size? Provide a rationale for your answer.

7. In the discussion section of the research article, the authors stated that sedative music had a large effect size when compared to both usual chair rest (>1.0) and scheduled chair rest (>0.9). Furthermore, scheduled chair rest when compared with usual chair rest did not result in significantly less anxiety, pain sensation, or pain distress, but the differences were in the expected direction with small to medium effects (0.20 to 0.45). Why is this information important for future research?

JUS 302

CHAPTER 9: HOMEWORK

NOTE: Please remember to restate the problem on your homework when submitting your answers.

 1. Define “power” and “effect” and illustrate the relevance of each concept utilizing an original example. (1-2 paragraphs)

2. In 1-2 paragraphs describe when it is appropriate to set up your alternative hypothesis as a directional as opposed to a non-directional hypothesis.

3. An independent-measures research study uses two samples, each with n = 8 participants. If the data produce a t statistic of t = 2.10, what would your decision be with regard to your null hypothesis (i.e. reject, fail to reject). To get full credit for your answer you need to show how you got your critical value and describe your rationale for your final conclusion---i.e. [show calculation of critical value]; critical value is plus or minus 1.96, so we would fail to reject the null hypothesis because...).

Hint: you need to calculate the critical value based on the appropriate degrees of freedom; also, in evaluating the one tailed hypotheses, assume that the nature or direction of any difference you find is consistent with the alternative/research hypothesis).

 a) For a two tailed hypothesis test (with alpha=.01)

 b) For a one tailed hypothesis test (with alpha= .01)

 c) For a two tailed hypothesis test (with alpha=.05)

 d) For a one tailed hypothesis test (with alpha=.05) JUS 302 

Main Task: Application � Non-Parametric Tests
You will submit one Word document for this activity. In the first part your activity document, provide short answers to the following questions (250 words or less). 

Part A. Questions about non-parametric procedures
1. What are the most common reasons you would select a non-parametric test over the parametric alternative? 

2. Discuss the issue of statistical power in non-parametric tests (as compared to their parametric counterparts). Which type tends to be more powerful? Why? 

3. For each of the following parametric tests, identify the appropriate non-parametric counterpart:

a. Dependent t test

b. Independent samples t test

c. Repeated measures ANOVA (one-variable)

d. One-way ANOVA (independent)

e. Pearson Correlation

Main Task: Submit the Following 
1. 
Calculate the sample size needed given these factors:

·         one-tailed t-test with two independent groups of equal size

·         small effect size (see Piasta, S.B., & Justice, L.M., 2010)

·         alpha =.05

·         beta = .2

·         Assume that the result is a sample size beyond what you can obtain. Use the compromise function to compute alpha and beta for a sample half the size. Indicate the resulting alpha and beta. Present an argument that your study is worth doing with the smaller sample.

2. 

·         Calculate the sample size needed given these factors:

·         ANOVA (fixed effects, omnibus, one-way)

·         small effect size

·         alpha =.05

·         beta = .2

·         3 groups

·         Assume that the result is a sample size beyond what you can obtain. Use the compromise function to compute alpha and beta for a sample approximately half the size. Give your rationale for your selected beta/alpha ratio. Indicate the resulting alpha and beta. Give an argument that your study is worth doing with the smaller sample.

Thanks & regards,

Ashit Jha