Take home problems for Exam 1

1. To study variation in income from state to state, researchers obtained a random sample of 5 states, and sampled median income from 5 counties in each state. The data are listed below.

1) Complete the ANOVA table and conduct a test of whether sigma a2 = 0.

2) Estimate the variance components for states and counties.

3) Calculate the estimate of intraclass correlation.

state      median income (in thousands)

California    51.564
California    44.102
California    57.647
California    70.247
California    61.985
Iowa          42.384
Iowa          46.994
Iowa          48.467
Iowa          35.035
Iowa          47.130
Missouri      51.476
Missouri      38.530
Missouri      34.007
Missouri      33.980
Missouri      32.620
Ohio          38.110
Ohio          45.659
Ohio          34.359
Ohio          41.672
Ohio          39.792
Vermont       52.135
Vermont       60.182
Vermont       51.993
Vermont       39.914
Vermont       46.912

2. Use the data from the meat storage experiment (in display 2.1) to determine how many samples would be needed in each group in a future experiment to the reject the null hypothesis at the .05 level of significance with power of at least .9, if the mean log counts in the four groups were 7, 6.5, 6, and 6.5.