# 420Hw12 - STAT 420(10 points(due Friday November 30 by 3:00...

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STAT 420 Fall 2007 Homework #12 (10 points) (due Friday, November 30, by 3:00 p.m.) 1. One Way ANOVA. Exercise 14.4 . Use the infmort data set where Y is income and the grouping variable is region (Asia, Europe, Americas and Africa). a) Draw a boxplot of income for each of the four regions. b) Compute the sample mean and sample variance for each of the regions. c) A visual inspection of the boxplots may lead us to conclude that the equal variance assumption may not be satisfied and that some transformation may be needed. Nevertheless, for the moment, let us fit the model Y i = μ 1 v 1 i + μ 2 v 2 i + μ 3 v 3 i + μ 4 v 4 i + ε i , where ε i ’s are iid N ( 0 , σ 2 ), and the indicator variables are v 1 i is 1 if the i -th country is in Asia and 0 otherwise, v 2 i is 1 if the i -th country is in Europe and 0 otherwise, v 3 i is 1 if the i -th country is in the Americas and 0 otherwise, v 4 i is 1 if the i -th country is in Africa and 0 otherwise. Suppose that you want to test the hypothesis that all population means are identical,

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## This note was uploaded on 04/29/2010 for the course STAT stat 420 taught by Professor Stepanov during the Spring '07 term at University of Illinois at Urbana–Champaign.

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420Hw12 - STAT 420(10 points(due Friday November 30 by 3:00...

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