week4-confidence+intervals

week4-confidence+intervals - #1.Sampleaccuracy theresearch...

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#1. Sample accuracy:  Researchers must have some sense of how good the sample must be to meet the objective to  the research.  Sample must be adequate for the task of making reasonably accurate generalization  about the population.  1
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St a t i s t i c vs . Pa r a me t e r Sample Statistic Population Parameter Mean x μ (mu) Proportion p π (P) Standard Deviation s σ (sigma) s . e = σ/ n n= s a mpl e s i z e - St a nda r d de vi a t i on: s t a t i s t i c a l me a s ur e of popul a t i on he t e r oge ne i t y f or a qua nt i t a t i ve va r i a bl e - St a nda r d e r r or : t he de gr e e of e r r or i n a s a mpl e e s t i ma t e ; t he a ve r a ge a mount by whi c h a s a mpl e e s t i ma t e de vi a t e s f r om t he popul a t i on va l ue i t 2
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Sa mpl e s i z e a nd St a nda r d Er r or Pr opor t i on va r i a bl e p = s a yi ng ye s q = s a yi ng no ( 1- p) - We don’ t know wha t r e a l π ( pa r a me t e r ) i s , but we t a ke a r a ndom s a mpl e of n. p = x/ n p i s t he numbe r of t hos e s a yi ng ye s ( x) i n t he s a mpl e , di vi de d by t he s a mpl e s i z e n. Ex. i f p=. 65 a nd we ha ve s a mpl e d n=1000, we f ound x=650 s a yi ng ye s . 3
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St a nda r d Er r or We c a n’ t know t he pr e c i s e di f f e r e nc e be t we e n π a nd p be c a us e we don’ t know t he va l ue of π ( r e a l pe r c e nt
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This note was uploaded on 11/20/2011 for the course SOCIOLOGY 920:311 taught by Professor Phillips during the Fall '10 term at Rutgers.

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week4-confidence+intervals - #1.Sampleaccuracy theresearch...

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