Statistics > SOLUTIONS MANUAL > University of Waterloo STAT 431 Assign2_Solutions (All)

University of Waterloo STAT 431 Assign2_Solutions

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STAT 431/831 ASSIGNMENT 2 DUE: OCTOBER 21, 2008 1. [9 points] A sample of 146 five-year-old children had their teeth examined and those with decayed, missing, or filled teeth (dmft) were noted. From ... their address it was also determined whether their drinking water was fluoridated. Finally, on the basis of various sociological measurements, their social class was designed as I,II,III, or unclassifiable. The data are given in Table 2. Table 2. Fluoridation and Dental Health Class I Class II Class III Unclassified Total Fluoridated 12/117 26/170 11/52 24/118 73/457 Unfluoridated 12/56 48/146 29/64 49/104 138/370 Note: Each entry gives the number of children with dmft from the total number of children in that cell (Carmichael et at., 1989). (a) [3 points] Test the hypothesis that the effect of fluoridation does not depend on social class. To do this, let’s first input the data. # Input the data teeth.dat<-read.table("teeth.dat",header=T) # Create indicator variables for class using a treatment contrast teeth.dat$classf<-factor(teeth.dat$class) teeth.dat$classft<-C(teeth.dat$classf,treatment) # Construct the response variable for logistic regression teeth.dat$resp<-cbind(teeth.dat$y,teeth.dat$m-teeth.dat$y) # Display the matrix of data [Show More]

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