chapter 3 producing data 產生資料
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Chapter 3 Producing Data 產生資料. 3.1 Designing Samples 3.2 Designing Experiments. 動機. 從 ( 少量 ) 的樣本 (samples) 推估母體 (population) 的特性 選用可代表母體的樣本 以儘可能不干擾母體的情況下取得資訊. 觀察 vs. 實驗. 觀察性研究 (observational study) 。 對每一個體僅做觀察並量測有興趣的變數,並不試圖影響反應值。 抽樣調查 (sample survey) 。 實驗性研究 (experimental study) 。 - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 3
Producing Data 3.1 Designing Samples3.2 Designing Experiments
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()(samples)(population)
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vs. (observational study)(sample survey)(experimental study)(treatment) (randomized comparative experiments)
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3.1
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(Confounding)()(Confounding)():()
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3.1 Designing Samples
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(population) (sample)(sample design)
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(voluntary response sample)Call-in(convenience sampling)(bias)
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(0~1)(probability sample)
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(Simple Random Sample) n n (Simple Random Sample, SRS) (table of random digits)
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(systematic random sample) n N N/n = k1~k a{a, a+k, a+2k, , a+(n-1)k} n n
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12301 213069051 64817 87174 09517 84534 06489 87201 9724510 2 69 05 16 48 17 87 17 40 95 1700, 31~99 05, 16, 17, 17, 171710 2 84 53 40 64 89 87 20 19 72 45 20, 1905, 16, 17, 20, 19
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(Stratified Sample)(stratum)SRS
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(ASCAP)$ 435(53)() ()()4326
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(Multistage Samples)(multistage sample design)SRS
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2007(Primary Sampling Units, PSUs)754 PSUs428PSUs PSU(blocks)()(cluster)
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(undercoverage)(homeless)(nonresponse) (response bias)
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It is estimated that disposable diapers account for less than 2% of the trash in todays landfills. In contrast, beverage containers, third-class mail and yard wasters are estimated to account for about 21% of the trash in landfills. Given this, in your opinion, would it be fair to ban disposable diapers?
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()1992Does it seem possible or does it seem impossible to you that the Nazi extermination of the Jews never happened?---22%possibleDoes it seem possible to you that the Nazi extermination of the Jews never happened, or do you feel certain that it happened?---1%possible
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()Never trust the results of a sample survey until you have read the exact questions posed.The amount of nonresponse and the date of the survey are also important.Good statistical design is a part, but only a part, of a trustworthy survey.