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ANOVA Practice1 ANOVA Unit 4 Analysis of Variance “A one-way ANOVA, or single factor ANOVA, tests differences between groups that are only classified on one independent variable.... The advantage of using ANOVA rather than multiple t-tests is that it reduces the probability of a type-I error.” (source: http://www.georgetown.edu/departments/psychology/researchmethods /statistics/inferential/anova.htm ) http://www.georgetown.edu/departments/psychology/researchmethods /statistics/inferential/anova.htm Photo source: http://i.zdnet.com/blogs/bad-leadership-causes-failed-it.jpg
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ANOVA Practice 2 Remember what we said about error? LESS SERIOUS: A type I error occurs when the null hypothesis is rejected when it is in fact true; that is, H0 is wrongly rejected. MORE SERIOUS: Type II error occurs when the null hypothesis H0, is not rejected when it is in fact false. A type II error is frequently due to sample sizes being too small.
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ANOVA Practice 3 Unit or Week 4 Practitioner's Work Scenario 1 Step 1: Take this motivation to lead test: http://www.mindtools.com/pages/article/newLDR_01.htm Determine your score: 14 – 27 This implies a low motivation to lead 28 - 55 This implies some uncertainty over your motivation to lead 56 - 70 This implies a strong motivation to leadhttp://www.mindtools.com/pages/article/newLDR_01.htm Now you are familiar with the test we will use for the hypothetical example.
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ANOVA Practice 4 Step 2: Calculate the problem using an ANOVA comparing groups using an appropriate program. Explore: ANOVA: http://www.openepi.com/Menu/OpenEpiMenu.htm http://www.openepi.com/Menu/OpenEpiMenu.htm Research question: Is there a difference among students of different majors in their leadership motivation. Operational definition: Leadership motivation is the score motivation to lead others according to the score on Mind Tools Leadership Motivation Assessment Measure.
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ANOVA Practice 5 Scenario 1: Imagine that we have four groups. Group A: A random sample group of first year communication majors take the Motivation to Lead test. Group C: A random sample group of communication majors who graduated from Park University take the Motivation to Lead test. Group D: A random sample group of communication and leadership MA graduate program majors who graduated from Park University take the Motivation to Lead test.
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ANOVA Practice 6 Here are the scores for each group: A B C 61 57 66 58 58 67 59 60 69 60 57 68 61 58 67 58 55 61 60 58 58 61 60 59
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ANOVA Practice 7 Step 2 Calculate the problem using an ANOVA comparing groups. You can use an online calculator (Internet), Microsoft Office Excel, or SPSS.
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ANOVA Practice 8
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9 Here is an example ANOVA calculator.
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ANOVA Practice 10
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ANOVA Practice 11 Results, then check table.
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ANOVA Practice 12 Answer is -10.5, which is below significance level indicated on this chart.
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ANOVA Practice 13 You can use SPSS and open data file from Excel
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ANOVA Practice 14 Open Excel and Enter Data
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ANOVA Practice 15 You can calculate an ANOVA—also called “F test”--in Excel if you have a version that provides ANOVA calculation. Enter data into data table. Depending on your version, go to TOOLS > DATA ANALYSIS Select “ANOVA single” Enter input range—this will be all of your data (you can simply draw a box around your data table) Alpha is preset at.05. Set output—where do you want your data to go? It can either go on the same sheet, on a different sheet, or in a whole new workbook. Hit “OK”
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ANOVA Practice 16
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ANOVA Practice 17 Compare Means - ANOVA Dependent variables are the two post tests.
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ANOVA Practice 18 Select.05 level significance.
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ANOVA Practice 19
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ANOVA Practice 20 There doesn ’ t seem to be any difference among majors regarding their leadership motivation. Remember, this is fictional data in a fictional study, just to provide an example. That’s all for this practice session. I sincerely appreciate your effort in this course!
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