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ANOVA Practice 1
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 )
Photo source: http://i.zdnet.com/blogs/bad-leadership-causes-failed-it.jpg
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.
ANOVA Practice 3
Unit or Week 4 Practitioner's Work Scenario 1Step 1: Take this motivation to lead test: http://www.mindtools.com/pages/article/newLDR_01.htm Determine your score:14 – 27This implies a low motivation to lead28 - 55This implies some uncertainty over your motivation to lead56 - 70This implies a strong motivation to lead
Now you are familiar with the test we will use for the hypothetical example.
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
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.
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.
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
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.
ANOVA Practice 8
ANOVA Practice 9
Here is an example ANOVA calculator.
ANOVA Practice 10
ANOVA Practice 11
Results, then check table.
ANOVA Practice 12
Answer is -10.5, which is below significance level indicated on this chart.
ANOVA Practice 13
You can use SPSS and open data file from Excel
ANOVA Practice 14
Open Excel and Enter Data
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”
ANOVA Practice 16
ANOVA Practice 17
Compare Means - ANOVA
Dependent variables are the two post tests.
ANOVA Practice 18
Select .05 level significance.
ANOVA Practice 19
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!