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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 Presentation
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Chapter 3
Producing Data 3.1 Designing Samples3.2 Designing Experiments
()(samples)(population)
vs. (observational study)(sample survey)(experimental study)(treatment) (randomized comparative experiments)
3.1
(Confounding)()(Confounding)():()
3.1 Designing Samples
(population) (sample)(sample design)
(voluntary response sample)Call-in(convenience sampling)(bias)
(0~1)(probability sample)
(Simple Random Sample) n n (Simple Random Sample, SRS) (table of random digits)
(systematic random sample) n N N/n = k1~k a{a, a+k, a+2k, , a+(n-1)k} n n
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
(Stratified Sample)(stratum)SRS
(ASCAP)$ 435(53)() ()()4326
(Multistage Samples)(multistage sample design)SRS
2007(Primary Sampling Units, PSUs)754 PSUs428PSUs PSU(blocks)()(cluster)
(undercoverage)(homeless)(nonresponse) (response bias)
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?
()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
()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.