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 mustprint 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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