Biostats SDS 328M Homework 7 Write your answers onto one or more separate sheets of paper. Clearly mark each sheet with your name and your lab section. Show your work and round all answers to at least 3 decimal places. Assume, unless otherwise noted, that =.05 1. As part of a study of environmental influences on sex determination in the fish Menidia, eggs from a single mating were divided into two groups and raised in either a warm or a cold environment. The data show that 65 of 141 offspring in the warm environment and 107 of 169 offspring in the cold environment were females. a. Test the hypothesis that the distribution of female and male fish follows a 1:1 ratio in the cold environment. (4 points) b. Name the test that you can use to calculate the exact p-value for your analysis in (a). (1 point) c. Suppose you want to test the hypothesis that the distribution of males and female fish Menidia is equal in the warm as in the cold environment. State the appropriate hypotheses for this analysis. (2 points) d. What are the odds of the fish in the cold environment being female? (1 point) e. Calculate the odds ratio of the fish being female in the cold environment compared to the fish in the warm environment. Interpret this ratio in the context of the question. (3 points) 2. Marine biologists have noticed that the color of the outermost growth band on a clam tends to be related to the time of the year in which the clam dies. A biologist conducted a small investigation of whether this is true for the species Protothaca staminea. She collected a sample of 78 clam shells from the species and classified them according to the month when the clam died and the color of the outermost growth band. The data are provided below: Clear Color Dark Unreadable February 9 25 7 March 15 18 4 a. Create an appropriate graph to display this data. (2 points) b. Is there a significant difference in the color distribution between clams that died in February and March? Show your work and include all steps for full credit. (5 points) 3. Are mice right-handed or left-handed? To answer this question, a researcher tested 320 mice of the same breed for paw preference. He observed which forepaw - right or left - the mice used to retrieve food from a narrow tube. Each mouse was tested 50 times, the results were as follows: Right Number of observations Left 7,871 8,129 Would you be able to conduct a chi-square test to determine if there is a preference for right or left paw among mice? Explain why or why not. (2 points)