# Biological Data Analysis: Homework 6

## Due Tuesday, Oct. 14

**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. **Calculate the residuals (each observation minus the mean for its group) for the data set you collected for homework 4 (or the data set you collected for homework 5, if you needed a new one). Plot a histogram of the residuals, using the spreadsheet linked from the normality page. In addition to printing the histogram, state your opinion about whether the data look normal enough for an anova.

**2. **Put the standard deviations for your groups in a table, and state your opinion about whether they're homoscedastic enough for an anova.

**3. **Perform a one-way anova on the data you collected for homework 4, using the spreadsheet linked on the one-way anova page. Report the F-statistic, the P-value, and how the variance is partitioned.

**4. **Plot a bar graph of your data, with the means arranged from smallest to largest. Show the results of the Tukey-Kramer test on the graph.

**5. **Perform a one-way anova on the data you collected for homework 4, using SAS. Print your SAS program and the output (the .lst file). If you didn't get a .lst file, or if your P-value was different from the spreadsheet results, print the .log file. If you couldn't get SAS to work last time, be sure to look at the introduction to SAS and the sample program on the one-way anova page, and get an early start on this so you can e-mail me if you have problems.

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Biological Data Analysis syllabus

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This page was last revised October 8, 2014. Its URL is
http://udel.edu/~mcdonald/stathw6.html