Stat 511 Final Exam S2009 Key

# Stat 511 Final Exam S2009 Key - Stat 511 Final Exam May 4...

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1 Stat 511 Final Exam May 4, 2009 Prof. Vardeman ( This exam will scored on a 160 point basis. ) I have neither given nor received unauthorized assistance on this exam. ________________________________________________________ Name _______________________________________________________________ Name Printed

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2 1. A marketing study used as an example in Neter et al. concerned counts of customers visiting a particular lumber store during a two-week period from each of 110 n different census tracts (these are metropolitan areas with populations of about 4000 residents each). Various demographic characteristics of the tracts were also obtained. Available for each tract are 1 2 3 the number of customers visiting the store from the tract the number of housing units in the tract the average personal income in the tract (dollars/year) the average housing unit age in the t y x x x 4 5 ract (years) the distance from the tract to the nearest competing store (miles) the distance from the tract to the store (miles) x x Here we will model customer counts as independent Poisson variables with E ii y and 0 1 12 23 34 45 5 ln i i i i xxxxx There is an ± output for these data attached to this exam. Use it to help you answer the following. a) In the presence of all other predictors, which of the 's x appears to be least important to the description of y ? Explain . b) What are approximate 95% confidence limits for the log-mean number of visits by tract #1 customers in a two week period? What are corresponding approximate 95% limits for the mean number of such visits? 8 pts 8 pts
3 c) Find an appropriate prediction standard error for the number of visits in a future two week period by tract #1 customers. (Hints: 01 12 23 34 45 5 ln bb xb x . How is a standard error for ˆ exp ln related to a standard error for ln ? How is Var new Y related to ?) d) Census tract #41 has one of the largest values of y

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## This note was uploaded on 02/11/2012 for the course STAT 511 taught by Professor Staff during the Spring '08 term at Iowa State.

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Stat 511 Final Exam S2009 Key - Stat 511 Final Exam May 4...

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