PSY 429 Experimental Psychology

Class Exercise #6

 

Homogeneity of Variance Test (Hartley's F_max Test)

One-Way Independent-Measures Analysis of Variance

 

1. What are the assumptions which should be met if you want to use an independent-measures ANOVA?

2. What would a relatively large value for F-max indicate?

3. If you compare the F-max value that you computed for the sample data with the critical value found in the F-max table and if the F-max you computed is larger than the critical value (in table), what would you conclude?

4. If two independent samples each having n = 10 and the sample variances are 12.34 and 9.15 for the two samples, calculate a homogeneity of variance test and determine whether the variances are equal. (Use Hartley's F-max test.)

5. Do weather conditions affect people's moods? To examine this question, a researcher randomly selected three samples of college students and administered a mood inventory questionnaire to each student. One group was tested on a dreary, overcast, and drizzly day. The second group was tested during a violent thunderstorm, and the third group was tested on a bright sunny day. Does the following data indicate that weather has an effect on mood?

a. Conduct an F-max homogeneity of variance test to determine whether an ANOVA is appropriate.

b. If the homogeneity of variance test indicates an ANOVA is appropriate, test if the weather has an effect on mood using the .05 level of significance.

c. Put the results into an ANOVA summary table.

d. Describe the results of this experiment, including any descriptive statistics (mean, standard deviation) which would help the reader to understand the results.

 

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