# Biological Data Analysis: Homework 10

## Due Tuesday, November 17

**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. **Collect data suitable for linear regression/correlation. You must collect the data yourself, by measuring something, counting something, or surveying people. You must collect biological data--data on living or dead organisms of some kind (and no, M&Ms don't count). You must have at least 20 observations.

For your answer to question 1, just describe what you measured; you'll include the data in your SAS program.

**2. **Draw a computer-generated graph of your data.

**3. **Based on looking at the graph, do you think linear regression/correlation, polynomial regression, or Spearman's rank correlation, would be most appropriate? Explain why you think that.

**4. **Analyze your data using linear regression/correlation. Report the P-value and the r^{2}. Use both my spreadsheet and SAS. Print your SAS program. You only need to print the log file and output if the SAS results don't agree with my spreadsheet.

**5. **Analyze your data using polynomial regression, using my spreadsheet. Report the P-value and r^{2} for the linear, quadratic, and cubic equations. You don't need to do the quartic or quintic, they're stupid. Also report the P-values for the increase in r^{2} between linear and quadratic, and between quadratic and cubic. Print the graphs with the quadratic and cubic lines fitted to the points.

**6. **Analyze your data with Spearman's rank correlation, using my spreadsheet. Report the P-value.

**7. **Now that you've analzyed your data three different ways, which technique do you think is best for your data? Why?

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Biological Data Analysis syllabus

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This page was last revised October 28, 2015. Its URL is
http://udel.edu/~mcdonald/stathw9.html