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Stats Letter - not because it would have been much more...

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Dear Professor Gould, Please look at problems 2e and 4a. For 2e, I had chosen iv as my answer because through calculating np = 20 (.3) = 6, I assumed the distribution of sample proportions could not be modeled normally. The sample size is too small to have at least 10 “successes” and thus in turn the standard deviation could not have been appropriately used to calculate the spread (standard deviation is applied to normally distributed models). In this case, we could only predict inaccurately a standard deviation that fails to reflect the true spread of the distribution so standard deviation should not be applied. For 4a, I had chosen iii as my answer because in answer i the phrasing of the question makes it seem as though the researchers could not control the caffeine intake of the women for such a great length of time. However this statement is inaccurate since it is possible for the researchers to have controlled caffeine intake of the women but they did
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Unformatted text preview: not because it would have been much more expensive to do so, another reason why these researchers probably chose to analyze an observational study instead of performing an actual experiment on women age 65 and older. By saying they could not makes it seem as though they are incapable of controlling the caffeine intake so this answer choice would not be the best answer. I felt that iii was the best answer because this study is evidently observational because there was no control group since the researchers themselves did not manipulate the caffeine intake of women and block the experiment into a control group and groups in which caffeine intake was altered but rather analyzed existing data. Thank you for taking the time to reconsider my score and reviewing my test. Sincerely, Stephanie Lee 603904125...
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This note was uploaded on 01/21/2011 for the course STATS 10 taught by Professor Ioudina during the Spring '08 term at UCLA.

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