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. Here are some data on the abundance of the tesselated darter, Etheostoma olmstedi, in streams in Maryland. The data are presented as number of fish per 75 meter section of stream. For each stream, data from two sections are given: one section adjacent to a pasture, and the other section not adjacent to a pasture. You want to know whether streams adjacent to pastures have the same density of tesselated darters as streams not adjacent to pastures. Analyze the data using: a regular t-test; a paired t-test; Wilcoxon's signed ranks test; and a sign test. Write a sentence or two interpreting the result of each test. Write a sentence or two explaining which you think the most appropriate test for these data would be, and why.
stream pasture other Andover Branch 0 31 Basin Run 52 21 Big Pipe Creek 2 0 Bynum Run 30 14 Carroll Branch 19 19 Delaware Run 10 0 East Br. Patapsco River 3 2 Gillis Falls 7 1 Gunpowder Falls 1 1 Israel Creek 22 30 Jones Falls 10 8 Little Deer Creek 21 60 Mason Branch 74 111 Middle Run 21 2 Northeast Creek 79 78 Patapsco River 54 4 Piney Run 4 2 Pomonkey Creek 2 0 Prettyboy Branch 2 0 Principio Creek 22 58 Red Lion Branch 55 23 Tuscarora Creek 1 0 Winters Rn 75 116
2. Write an exam question for which the correct answer is one of the tests that only involves attribute variables (tests of goodness-of-fit and independence). Make it in the same format as the questions on the exams: describe a biological experiment, mention the biological question to be answered, and ask which test is the best. Be sure to give the answer.
3. Write an exam question for which the correct answer is one of the tests involving a measurement variable (anovas, their non-parametric analogues, etc.).
4. I'm constantly trying to improve the web pages for this class. To help me, go to the web page listed below with a number that corresponds to your birth date and critique it. Your critique can consist of general comments typed in your homework, and specific comments that you write on a printout of the web page (spelling mistakes, unclear sentences, ugly format, etc.).
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This page was last revised November 2, 2007. Its URL is http://udel.edu/~mcdonald/stathw8.html