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Unformatted text preview: Quiz 10 Solutions Course: Stat 231 Term: Spring 2010 Instructor: Dr. Jock MacKay Prepared by: Murshid Kuttihassan 1. Is this an experimental or observational plan? Answer: A: experimental In an experimental plan, the investigators set the value of the explanatory variate on each unit in the sample. Here the explanatory variate is the type of coating and the investigators decide which section is coated with what type. 2. Burying the two halves of the pipe together will prevent confounding due to Answer: B: z 2 only. By burying together both halves will be exposed to the same level of acidity of the soil and hence any differ- ence in the level of corrosion will be due to factors other than soil acidity. However, burying together can not ensure same carbon concentration in the pipe as the carbon concentration is determined when the pipe is manufactured. 3. Burying the pairs of pipe in a variety of conditions will help to reduce Answer: B: study error The target population is pipes buried under all possible environmental conditions. By burying the pairs of pipe inThe target population is pipes buried under all possible environmental conditions....
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- Spring '10