Statistics

Complete questions 4, 5, and 16. Use SPSS, a calculator, or spreadsheet to complete the statistical portions of the questions.

For questions 4 and 5, your responses should be in the form of a short paragraph (3–5 sentences).

(4) Explain why you should use ANOVA instead of several \(t\) tests to evaluate mean differences when an experiment consists of three or more treatment conditions.

(5.) Posttests are done after an analysis of variance.

1. What is the purpose for posttests?
2. Explain why you would not do posttests if the analysis is comparing only two treatments.
3. Explain why you would not do posttests if the decision from the ANOVA was to fail to reject the null hypothesis.

For question 16, provide both the statistical calculations used as well as a reproduction of the table with information provided. Also provide a short explanation of what the results of the test mean for the success of the experiment.

16. The following summary table presents the results of an ANOVA from an experiment comparing four treatment conditions with a sample of $n=10$ in each treatment. Complete all missing values in the table. (Hint: Start with the df column.)

SPSS Assignment

• Enter the data for Chapter 13, question 7 into SPSS.
  7. In the previous problem the treatments were significantly different primarily because the mean for sample III is noticeably different from the other two samples \(\left(M_{1}=3, M_{2}=4\right.\), and \(M_{3}=8\) ). For the following data, we have taken the scores from Problem 6 and reduced the differences between treatments.
  Specifically, we have subtracted 3 points from each score in the third sample to produce sample means of \(M_{1}=3, M_{2}=4\), and \(M_{3}=5\).
  a. Before you begin any calculations, predict how the changes in the data should influence the outcome of the analysis. That is, how will the \(F\) -ratio for these data compare with the \(F\) -ratio from Problem 6 ?
  b. Use an analysis of variance with \(\alpha=.05\) to determine whether there are any significant differences among the three treatments. (Does your answer agree with your prediction in part a?)
  
• State the null and alternative hypotheses.
• Conduct a one-way ANOVA test at the .05 level.
• Copy or copy object and paste relevant output from the statistical test.
• State whether or not the null hypothesis is accepted or rejected based on the results of the statistical test. Use the conventions described by Gravetter and Wallnau on page 348 to present your report.

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Solution: The downloadable solution consists of 4 pages, 611 words and 1 charts.
Deliverable: Word Document