Objectives: The objectives of this lab are to analyze observational data using nonparametric statistics. Methods Students will learn to analyze observational data by using different nonparametric tests. The following tests will be employed: sign test, Mann Whitney U test, Kruskal Wallis Test and the Chi-Square test of independence. Directions on how to apply each test to different types of data are given on the handout. After learning how to apply each of these tests, students should indicate which test should be used to analyze the following experiments. Then they should analyze the results of each experiment using the appropriate test. The Mann-Whitney U test compares ordinal data for two different groups using ranks instead of the actual data. For this example, students can compare two groups that are not paired. The Kruskal-Wallis test also uses ranks and is applied to unpaired ordinal data that compare differences among three or more groups. The Kruskal Wallis test can be used to see if there is a difference among the groups. The sign test compares ordinal data that are paired. For example, how individuals behave in one situation can be compared with how those same individuals behave in a different situation. The data are paired because the same individual is compared in different situations. The Chi-Square test of independence examines categorical data. For example, you can analyze if there is a difference in how many males and how many females tended to climb over a barrier or stay in one place. Experiment #1 Researchers wanted to know if blue jays preferred peanuts over sunflower seeds. They placed 10 piles of peanuts, each next to a pile of sunower seeds, and watched for blue jays to arrive. They recorded how many of each type of seed was eaten by the blue jay. Pile # Number of peanuts eaten Number of sunower seeds eaten \\C'OO-JQ'J'ILUJNH HJQMMOLUJOOUN WMHLHMWMW 2 10 4 W Name of test used for analysis Test statistic Probability value p = Experiment #2 Researchers wanted to know if blue jays and mourning doves differed in the height they preferred to feed. A pile of mixed seeds was placed on the ground and a similar pile of seeds was placed on a platform Im high. They researchers watched the seeds for an hour and recorded the number of blue jays and mourning doves that fed on the seeds. Seeds on ground Seeds on elevated platform Blue jays 5 10 Mourning doves 10 5 Name of test used for analysis Test statistic Probability value p = Experiment #3 Researchers wanted to know if more birds preferred suet balls, sunflower seeds or safflower seeds. They hung suet balls in 5 trees, bird feeders with sunflower seeds in 5 different trees and bird feeders with safflower seeds in 5 more trees. They watched the trees for an hour and recorded how many different birds fed there. Number of birds per tree at: Suet ball trees Sunflower seed trees Safflower seed trees NOW3 9 N Name of test used for analysis Test statistic Probability value p = Experiment #4 Researchers wanted to know if squirrels would be repelled from eating sunflower seeds if the seeds were treated with hot pepper flakes. They placed feeders with 20 sunflower seeds in 10 trees and feeders with sunflower seeds treated with hot pepper flakes in 10 different trees. They watch the feeders for squirrel activity and recorded how many seeds remained after the squirrel had left. Number of sunflower seeds remaining Number of sunflower seeds treated with hot pepper flakes remaining 20 18 19 15 16 NWOANOVWHO 17 11 20 12 14 Name of test used for analysis Test statistic Probability value p =