Week_12_Practice_Problems

# Week_12_Practice_Problems - Week 12 Practice Problems 1...

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Week 12 Practice Problems 1. Formaldehyde is a gas to which some individuals have an allergic reaction. To see if UFFI (a type of insulation) is a significant source of formaldehyde in homes in Canada, 25 homes with UFFI were selected at random from a list of homes that had received a grant from the Federal Government to pay (in part) for the insulation. For each selected home, researchers chose another house located nearby and of the same age that did not have UFFI installed. Then the formaldehyde concentration (in parts per billion) was measured in each selected house. The data and some summaries are pair UFFI Control difference pair UFFI Control difference 1 44.3 44.2 0.1 14 57.7 55.1 2.6 2 55.3 54.9 0.4 15 51 52 -1 3 37.7 32.1 5.6 16 42.2 40.4 1.8 4 46 47 -1 17 51.7 47.5 4.2 5 42.7 42.5 0.2 18 47.1 45.4 1.7 6 57.4 52.3 5.1 19 49.6 49.5 0.1 7 44.3 44.2 0.1 20 52 48.9 3.1 8 45.7 39.3 6.4 21 56 53.3 2.7 9 58.2 55.2 3 22 51.5 45 6.5 10 37.5 36.2 1.3 23 53.5 48.8 4.7 11 40.6 34.8 5.8 24 59.7 54.2 5.5 12 55.7 53.8 1.9 25 54.8 51.3 3.5 13 51.9 52.4 -0.5 average 49.76 47.21 2.55 sd 6.58 6.7 2.42 a) Is this an experimental or observational plan? Explain. b) What is the advantage of selecting the homes in pairs? We model the differences 12 { ,. .., } 5 y y because we suspect that homes within each pair will be more alike than homes in different pairs. We have , ~ (0, ), 1,. ..25, ii i Y R R G i independent μ σ =+ = c) What does the parameter represent?

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Week_12_Practice_Problems - Week 12 Practice Problems 1...

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