Time to Practice: Week 4
Complete Parts A, B, and C below.
Part A
- Some questions in Part A require that you access data from Statistics for People Who (Think They) Hate Statistics. This data is available on the student website under the Textbook Resourceslink.
1. Using the data in the file named Ch. 11 Data Set 2, test the research hypothesis at the .05 level of significance that boys raise their hands in class more often than girls. Do this practice problem by hand using a calculator. What is your conclusion regarding the research hypothesis? Remember to first decide whether this is a one- or two-tailed test.
2. Practice the following problems by hand just to see if you can get the numbers right. Using the following information, calculate the t-test statistic.
a.
b.
c.
3. Using the results you got from Question 2 and a level of significance at .05, what are the two-tailed critical values associated with each? Would the null hypothesis be rejected?
4. Using the data in the file named Ch. 11 Data Set 3, test the null hypothesis that urban and rural residents both have the same attitude toward gun control. Use IBM® SPSS® software to complete the analysis for this problem.
5. In the following examples, indicate whether you would perform a t-test of independent means or dependent means.
a. Two groups were exposed to different treatment levels for ankle sprains. Which treatment was most effective?
b. A researcher in nursing wanted to know if the recovery of patients was quicker when some received additional in-home care whereas when others received the standard amount.
c. A group of adolescent boys was offered interpersonal skills counseling and then tested in September and May to see if there was any impact on family harmony.
d. One group of adult men was given instructions in reducing their high blood pressure whereas another was not given any instructions.
e. One group of men was provided access to an exercise program and tested two times over a 6-month period for heart health.
6. The data set for this problem can be found through the Sage Materials in the Student Textbook Resource Access link, listed under Academic Resources. For Ch. 12 Data Set 3, compute the t value and write a conclusion on whether there is a difference in satisfaction level in a group of families’ use of service centers following a social service intervention on a scale from 1 to 15. Do this exercise using IBM® SPSS® software, and report the exact probability of the outcome. Copy and paste the output from IBM®SPSS® into this worksheet.
You may use SPSS for this problem You may use SPSS for this problem or do it by hand. A1. famous brand-name manufacturer wants to know whether people prefer Nibbles or Wribbles. They sample each type of cracker and indicate their like or dislike on a scale from 1 to 10. Which do they like the most? Paste your t-test output into your answer and write a very brief analysis.
| Nibbles rating | Wribbles rating |
| 9 | 4 |
| 3 | 7 |
| 1 | 6 |
| 6 | 8 |
| 5 | 7 |
| 7 | 7 |
| 8 | 8 |
| 3 | 6 |
| 10 | 7 |
| 3 | 8 |
| 5 | 9 |
| 2 | 8 |
| 9 | 7 |
| 6 | 3 |
| 2 | 6 |
| 5 | 7 |
| 8 | 6 |
| 1 | 5 |
| 6 | 5 |
| 3 | 6 |
2. Using the following table, provide three examples of a simple one-way ANOVA, two examples of a two-factor ANOVA, and one example of a three-factor ANOVA. Complete the table for the missing examples. Identify the grouping and the test variable.
| Design | Grouping variable(s) | Test variable |
| Simple ANOVA | Four levels of hours of training—2, 4, 6, and 8 hours | Typing accuracy |
| Enter Your Example Here | Enter Your Example Here | |
| Enter Your Example Here | Enter Your Example Here | |
| Enter Your Example Here | Enter Your Example Here | |
| Two-factor ANOVA | Two levels of training and gender (two-way design) | Typing accuracy |
| Enter Your Example Here | Enter Your Example Here | |
| Enter Your Example Here | Enter Your Example Here | |
| Three-factor ANOVA | Two levels of training, two of gender, and three of income | Voting attitudes |
| Enter Your Example Here | Enter Your Example Here |
3. The data set for this problem can be found through the Sage Materials in the Textbook Resources link. Using the data in Ch. 13 Data Set 2 and the IBM® SPSS® software, compute the F ratio for a comparison between the three levels representing the average amount of time that swimmers practice weekly (< 15, 15–25, and > 25 hours) with the outcome variable being their time for the 100-yard freestyle. Does practice time make a difference? Use the Options feature to obtain the means for the groups. Copy and paste the output from IBM®SPSS® into this worksheet.
4. When would you use a factorial ANOVA rather than a simple ANOVA to test the significance of the difference between the averages of two or more groups?
5. Create a drawing or plan for a 2 × 3 experimental design that would lend itself to a factorial ANOVA. Identify the independent and dependent variables.
From Salkind (2011). Copyright © 2012 SAGE. All Rights Reserved. Adapted with permission.
Part B
Complete the questions below. Be specific and provide examples when relevant.
Cite any sources consistent with APA guidelines.
| Question | Answer |
| What is meant by independent samples? Provide a research example of two independent samples. | |
| When is it appropriate to use a t-test for dependent samples? What is the key piece of information you must know in order to decide? | |
| When is it appropriate to use an ANOVA? What is the key piece of information you must know in order to decide? | |
| Why would you want to do an ANOVA when you have more than two groups, rather than just comparing each pair of means with a t-test? |
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