# Biological Data Analysis: Homework 6

## Due Tuesday, Oct. 25

**You must type this and all other homework assignments. Do not e-mail the assignment to me; turn it in early (at 322 Wolf) for a foreseeable absence, or turn it in late after an unexpected absence from class. **

**1. **For homework 5, you looked at the normality and homoscedasticity of your data. Try to forget the results of your one-way anova; based on the normality and homoscedasticity of your data, which do you think would be most appropriate for analyzing you untransformed data: one-way anova; Welch's anova; or the Kruskal-Wallis test? Explain why you chose that test.

**2. **Now do a Welch's anova on the same untransformed data set that you did a one-way anova on last time. Then do the Kruskal-Wallis test on the same data set. Put the results in one table that shows the test statistic, degrees of freedom, and P-value for each test.

**3. **How do the results of the three tests compare? If you were evil or stupid, and looked at the three results *before* you decided which to choose, which one would you choose?

**Optional SAS question. From now on, each homework assignment will have a SAS question. These are completely optional, only do them if you want to teach yourself SAS. You will ***not* get extra credit, and there will not be SAS questions on the exams.

**4. **Do the Welch's anova and Kruskal-Wallis tests on your data set in SAS. Print your SAS program and output. If you don't get output (the .lst file), print the .log file so I can try to figure out what you're doing wrong.

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This page was last revised October 20, 2016. Its URL is
http://udel.edu/~mcdonald/stathw6.html