# Biological Data Analysis: Homework 8

## Due Tuesday, November 3

**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. **Every year, volunteers count birds in specific areas for the Audobon Society's Christmas Bird Count. You want to know whether the number of American black ducks (*Anas rubripes*) changed between 2013 and 2014 in Maryland. The number of American black ducks counted in each of 23 areas in Maryland is given below. Which test do you think would be most appropriate: a Student's t-test; a paired t-test; Wilcoxon's signed ranks test; or linear regression/correlation? Write a few sentences giving your reasons for choosing that test.

Location 2013 2014
Allegany County 1 11
Annapolis-Gibson Island 122 37
Bowie 51 30
Catoctin Mountain 0 8
Chesterville 754 239
Crisfield 423 119
Denton 7 19
Elkton 67 143
Jug Bay 657 477
Lower Kent County 1107 632
Oakland 51 50
Ocean City 844 759
Patuxent River 3 16
Point Lookout 6 8
Port Tobacco 57 54
Rock Run 116 49
Saint Michaels 47 32
Salisbury 39 62
Seneca 36 82
Southern Dorchester County 1441 397
Sugarloaf Mountain 71 57
Triadelphia Reservoir 24 91
Washington County 6 7

**2. **Analyze the data using whichever test you think is best. Use both a spreadsheet and SAS. Give the test statistic and P-value from the spreadsheet and from SAS. You **must**print your SAS program and your SAS output (the .lst file). If you can't get SAS to work, or you don't get the same P-value from SAS and the spreadsheet, you **must** e-mail me for help.

**3. **Now analyze the data using the other three tests; including what you did for question 2, you should have P-values from Student's t-test; a paired t-test; Wilcoxon's signed ranks test; and linear regression/correlation. You may use spreadsheets, web sites, or SAS for this. Give the P-values in a nice little table, and write a couple of sentences comparing the results of the tests.

**4. **Make a graph that summarizes the data from question 1 in what you think is the most effective way.

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