STA 6207 – Homework #4 – Due Wednesday 10/20/10 Part 1: Iron Levels in the Chesapeake Researchers measured iron levels at 6 depths in the Chesapeake River (depths=0,10, 30, 40, 50, and 100 feet). They took 3 replicates at the first 5 depths and 5 replicates at the sixth. a) Fit a simple linear regression, relating iron level to depth. Obtain the Analysis of Variance, R 2 , Parameter Estimates, Standard Errors, and conduct the F-test, and t-test to determine whether there is an association between iron level and depth ( α = 0.05). Obtain a plot of residuals versus depth. b) Conduct the F-test for lack of fit, by obtaining the means and variances separately for each depth, and using them and the fitted values from the linear regression to obtain the Sums of Squares for Pure Error and Lack of Fit. Test at α = 0.05 significance level. You can also obtain this directly from a program. Part 2: Mortgage Yields in U.S. SMSAs (Circa 1965) A study obtained mortgage yields in n=18 U.S. metropolitan areas in the 1960s.
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