Application: ANOVA Study: The Alpha Shoe Company
When you read published research studies, you find experimental studies in which one or more variables are manipulated. One example is a study on whether students with windows in their classrooms give their instructors higher evaluations than students with no windows in their classrooms. You could do a basic comparison of these two groups with a t test, which you studied in Week 4. Perhaps it would be more interesting to have additional levels of environment. You might compare instructor evaluations when students are in a class with no windows, a class with windows that look out to a parking lot, a class with windows that look out to a park, or a class with no windows but pictures of windows on the wall. Since you have multiple levels of the factor, environment, an ANOVA would help you understand the differences between each.
This Assignment will give you practice conducting a study with multiple levels of a factor by working once again with the Alpha Shoe Company. Since many research studies rely on the ANOVA for analysis, you will enhance your ability to understand the results of research studies that you evaluate in the future.
Scenario:
Imagine that Alpha Shoe Company wants to do a second study on the vertical lift basketball players can gain from their shoes. Recall that they believe that how high a player can jump is affected by the type of shoe that player wears. They identified 25 professional basketball players and randomly assigned each of them to wear one of the five types of shoe, then measured how high each player jumped. Each player's jumping height is given below in inches:
|
Pluto
|
Omega II
|
Beta Super
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Delta
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Gamma
|
|
29.1
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29.2
|
28.5
|
28.4
|
27.7
|
|
29.8
|
29.1
|
28.9
|
28.0
|
27.9
|
|
30.0
|
28.8
|
29.2
|
28.8
|
28.0
|
|
29.0
|
28.7
|
28.3
|
29.0
|
28.2
|
|
31.1
|
28.8
|
30.0
|
28.9
|
28.0
|
Assignment:
To complete this Assignment, answers to the following. Use SPSS to compare the means of the scores of these five shoes with a one-way ANOVA. Save and submit both your SPSS data file and your output.
• Before comparing the scores with an ANOVA, state your null and alternative hypotheses in words (not formulas).
• Identify the independent and dependent variables.
• Name the levels in your identified factor.
• State the within-group degrees of freedom and explain how you calculate it.
• State the between-group degrees of freedom and explain how you calculate it.
• Identify the obtained F value.
• Identify the p value.
• Explain whether the F test is significant. Explain how you know and what it tells you.
• Explain what you can conclude about the effect of shoe choice on vertical lift (jumping height).
• Should you conduct a post hoc test? Why or why not? If yes, conduct a Tukey HSD post hoc analysis. Explain what the results tell you about type of shoe choice and vertical lift.