Download Questions on Statistical Methods for Bioscience II - Assignment I | HORT 572 and more Assignments Data Analysis & Statistical Methods in PDF only on Docsity! Stat/For/Hort 572 Larget January 24, 2008 Assignment #1 — Due Friday, February 1, 2007, by 4:00 P.M. Turn in homework in lecture, discussion, or your TA’s mailbox. Please circle the discussion section you expect to attend to pick up this assignment. 311: Tues. 1:00–2:15 312: Wed. 2:30–3:45 313: Tue. 4:00–5:15 If you do not already have R installed on your computer, follow the example in class or from Appendix C in the textbook to install it. The last several problems depend on the data set cows.txt located in the homework area of the course web page. The file cows.info is a plain text file that contains information about the variables in cows.txt. Please download this file to your computer and use the read.data function to read the cows.txt file into R. I strongly recommend using the lattice package in R for graphics. You will need to download the lattice package. After starting R, load the lattice package with the command library(lattice). 1. Random variables X and Y have means µX = 12 and µY = 15, standard deviations σX = 3 and σY = 5 and correlation ρ = 0.5. What are the mean and standard deviation of the sum X + Y ? What are the mean and standard deviation of the difference X − Y ? 2. Use R to take a random sample of 10,000 binomial random variables with n = 50 and p = 0.1. Plot a histogram of the sample using the breaks argument so that each outcome is shown with its own bar. (You could use breaks=seq(-0.5,50.5) for the full range, but it is better to set the limits closer to the limits of your data.) Overlay on the histogram a normal curve with the mean and standard deviation. 3. Repeat the previous problem with n = 50 and p = 0.5. Which normal approximation is better. Why? 4. Compute the mean and standard deviation of the age of the cows in months. 5. Draw a histogram of the cow ages. Overlay on this histogram a normal curve with the mean and standard deviation you calculated in the previous part. Follow the example in the course notes. 6. Repeat the previous two problems for the cow ages in years. How do the mean and standard deviation change? 7. Use xyplot to plot the milk yield versus the initial weight of the cows. Describe the relationship between the variables. What method from last semester may be appropriate to analyze the relationship between these variables? 8. Use the bwplot to draw side-by-side boxplots of milk yield versus treatment. Describe the relationship between these variables. What method from last semester may be appropriate to analyze the relationship between these variables? Work to do, but not turn in. • Acquire the textbook. • Read Chapters 1–3.1, pages 1–32.
