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Take the McCroskey test yourself to see your apprehension level

Take the McCroskey test yourself to see your apprehension level. This PowerPoint will walk through the comparison of means of the pre and post-tests. Remember the Types of Scales?. Nominal Data (Chi-square) classification data, e.g. m/f

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Take the McCroskey test yourself to see your apprehension level

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  1. Take the McCroskey test yourself to see your apprehension level This PowerPoint will walk through the comparison of means of the pre and post-tests McCroskey Scenario t-test

  2. Remember the Types of Scales? Nominal Data (Chi-square) • classification data, e.g. m/f • no ordering, e.g. it makes no sense to state that M > F • arbitrary labels, e.g., m/f, 0/1, etc Ordinal Data(t-test) • ordered but differences between values are not important • e.g., political parties on left to right spectrum given labels 0, 1, 2 • e.g., Likert scales, rank on a scale of 1..5 your degree of satisfaction • e.g., restaurant ratings Interval Data • ordered, constant scale, but no natural zero • differences make sense, but ratios do not (e.g., 30°-20°=20°-10°, but 20°/10° is not twice as hot! • e.g., temperature (C,F), dates Ratio Data • ordered, constant scale, natural zero • e.g., height, weight, age, length • Quoted from http://www.stat.sfu.ca/~cschwarz/Stat-301/Handouts/node5.html McCroskey Scenario t-test

  3. Take McCroskey'sPRCA.  http://ww3.llcc.edu/speechsurvey/survey.aspx OR http://www.jamescmccroskey.com/measures/prca24.htm Photo Source http://2.bp.blogspot.com/_27z_ybX1fcc/SafUfnpKgwI/AAAAAAAAAI4/nwRnSJx33dw/s400/speakerbestself.jpg McCroskey Scenario t-test

  4. Study • Imagine that a group of 20 students enrolled in Dr. Cohn's public speaking course.  These students took McCroskey's test on the first day of their public speaking course.  Scores can range from 24-120, and a score above 65 suggests higher than average apprehension. Dr. Cohn is concerned that she has so many apprehensive students in the class.  Here are their scores: • After one term of instruction, Dr. Cohn administered the test at the end of the course because she wanted to see if taking the course lowered student apprehension.  • In this case, there is a pre-post test for one group and the data on a scale.  Dr. Cohn asks you to calculate the results using a t-test.  • Is there a significant difference in the communication apprehension level of the class members before and after taking Dr. Cohn's course? McCroskey Scenario t-test

  5. First, you enter the data. McCroskey Scenario t-test

  6. Pull down “Help,” select “Statistics Coach” if you need help. McCroskey Scenario t-test

  7. Compare means of the pre and post test. McCroskey Scenario t-test

  8. Select two McCroskey Scenario t-test

  9. Related data McCroskey Scenario t-test

  10. Normal Distribution McCroskey Scenario t-test

  11. The “Statistics Coach” help function guides you in what statistical test to use. McCroskey Scenario t-test

  12. What are the means to be compared? The average of the pretest, the average of the posttest. The calculator will figure this automatically as part of the t-test calculation. • Add the 20 scores from the pretest = 1600 • Divide by 20 students in the class = 80 is the average or mean for the pretest. • Add the 20 scores from the posttest = 1193 • Divide by 20 students in the class = 51 McCroskey Scenario t-test

  13. 95% confident that the difference is not by chance McCroskey Scenario t-test

  14. Enter Data McCroskey Scenario t-test

  15. From menu • Select “Analyze” • Select “Compare Means,” which is what a t-test does. • Select “Paired-Samples T Test,” which is what the Statistics Coach told us to do based on our answers to the various questions. McCroskey Scenario t-test

  16. McCroskey Scenario t-test

  17. If you don’t have SPSS, here is a calculator: http://www.physics.csbsju.edu/stats/t-test_bulk_form.html McCroskey Scenario t-test

  18. McCroskey Scenario t-test

  19. The standard deviation helps the researcher determine how much distance from the mean is typical and how much is considered significant.  McCroskey Scenario t-test

  20. Using unpaired t-testt= 4.46 sdev= 20.2 degrees of freedom = 38 The probability of this result, assuming the null hypothesis, is less than .0001 • Scores are significantly lower after the course. (Remember, this is fictional research.) • We can feel confident that completing the public speaking course helped lower student communication apprehension. McCroskey Scenario t-test

  21. Hope you enjoyed this application practice! McCroskey Scenario t-test

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