Exam Name___________________________________
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. Provide an appropriate response. 1) An agricultural researcher wishes to compare the yield of four different varieties of wheat. 64 plots of land are available for an experiment. On each plot of land one of the varieties of wheat will be grown. At the end of the experiment the yield for the different varieties will be compared. 32 of the plots are at one site (site A) and the other 32 are at another site (site B). The soil at site A differs significantly from the soil at site B. If the researcher wishes to design an experiment using randomized block design, how could the wheat varieties be assigned to the different plots?
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Answer: Answers will vary. Possible answer: Randomly divide the 32 plots at site A into four groups of 8 plots each. Randomly assign each group of plots to a different variety of wheat. Randomly divide the 32 plots at site B into four groups of 8 plots each. Randomly assign each group of plots to a different variety of wheat. Explanation: 2) Describe the steps involved when using stratified random sampling with proportional allocation. What are the advantages of this sampling method?
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Answer: Answers will vary. Possible answer: The population is first divided into subpopulations (strata). From each stratum, a simple random sample is obtained whose size is proportional to the size of the stratum. The advantage of this method is that it ensures that no stratum is missed. Explanation: 3) A college lecturer has devised a new method of teaching a particular mathematical concept and wishes to try out this teaching method on a representative sample of his students. There are 76 students in his class and he wishes to obtain a simple random sample of 25 of them. Describe a method which would be unlikely to yield a representative sample. Answer: Answers will vary. Possible answer: The lecturer stands at the door of his classroom and tells the first 25 students to arrive to class that they are invited to a special bonus session of class to be held at some upcoming date. This is unlikely to yield a representative sample as the students who show up to class first could possibly be the ones who are more conscientious and hard-working. Or, the students may refuse to volunteer for an extra class period, so the lecturer's sample would be too small to be a representative sample. Explanation:
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