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Unformatted text preview: Biological Statistics I Biometry 3010 / Natural Resources 3130 / Statistical Science 2200 Lab 4 Jennifer Chung Section 401 10/03/11 In today’s lab we shall examine the average length of brown trout from samples taken from two streams in the Catskills (real data!). Stream 1 was sampled on 4/01/1998 ( trout040198.txt ), while Stream 2 was sampled on 4/02/1998 ( trout040298.txt ). We wish to test the hypothesis that both sets of trout come from the same population. Historically one-year-old brown trout average about 194 mm in length, while two-year-old brown trout are much larger. We can reject the hypothesis that these are one-year-old trout if the mean size of the sample is significantly different than 194 mm. That will be the essence of today’s exercise. In addition, we shall learn about setting up plots for data comparison and tables for comparisons of analyses. Import the data trout040198.txt and trout040298.txt into R. It might be easiest to create a script using the R editor to create the code you need, execute it and save it for future reference. Have your TA explain how to do this if you do not know already. 1. (5 points) To quickly examine the data use the boxplot command to give you some indication of which, if any of these two data sets contains fish that are not similar in average size to one-year-old brown trout: boxplot(trout040198[,1],trout040298[,1], names= c('Trout 4/01/1998','Trout 4/02/1998'), ylab='Trout Length (mm)') Make the plot relatively small to save space. trout040198 = read.table("C:\\Users\\B30A\\Desktop\\trout040198.txt") > trout040298 = read.table("C:\\Users\\B30A\\Desktop\\trout040298.txt") > boxplot(trout040198[,1],trout040298[,1], + names= + c('Trout 4/01/1998','Trout 4/02/1998'), + ylab='Trout Length (mm)')...
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