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Unformatted text preview: Two Independent Populations If an estimate is an unbiased such as sample mean, then it is a good idea to pool the estimates to get a single estimate from several relatively small samples. The pooled estimate is a “good” estimate when compared with each individual estimates. Pooled Mean: Supposed we have m number of estimates (i), of sample size n(i), for the population expected value μ , the pooled estimate is: [ Σ n(i) (i)] / [ Σ n(i)], both sums are over all values of i = 1, 2,. . ., m. Pooled Variance: Since the sample variance is also unbiased estimate of population variance σ 2 , therefore, it is a good idea to pool the estimates to get a single estimate from m number of estimates S(i) 2 , of sample size n(i), the pooled estimate is: {[ Σ [n(i) – 1] S(i) 2 ] } / {[ Σ n(i)] – m}, both sums are over all values of i = 1, 2,…, m. We pool variance estimates for other good reasons. Depending on a particular reason, then the conclusion might have to be made explicitly conditional on e.g., the validity of the equalconclusion might have to be made explicitly conditional on e....
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This note was uploaded on 10/05/2011 for the course ECO 6416 taught by Professor Staff during the Spring '08 term at University of Central Florida.
 Spring '08
 Staff

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