lbw <- read.table("Oct.dat") ; attach(lbw)
iqfull <- V1;  rcomp <- V4; rrate <- V5 ; racc <- V6 
 bw  <- V8 ; rbw  <- V9; ga  <- V10; sex <- V11
  
  pdf("LbwR.pdf") 
 split.screen(c(2,2))
 screen(1) 
 plot(bw,rrate, xlab="Birth weight (kg)", ylab="Reading rate")
 #   main="Plot of Reading rate against birth weight")
 screen(2) 
 plot(rbw,rrate, xlab="Expected birth weight", ylab="Reading rate")
   #  main="Plot of Reading rate against expected birth weight for gestational age")
screen(3)
  plot(iqfull,rrate, xlab="IQ score", ylab="Reading rate")
   #  main="Plot of Reading rate against Reading comprehension")
screen(4) 
  plot(ga,rrate, xlab="Gestational age (weeks) ", ylab="Reading rate")
    # main="Plot of Reading rate against gestational age ")
    dev.off()   
    
  rlm <-  lm(rrate ~ iqfull) ; rrbw <- lm(rrate ~ rbw) 
  rsex <- lm(rrate ~ sex ) ; rga <- lm(rrate ~ ga)  
  summary(rlm); summary(rrbw); summary(rsex); summary(rga);  

  riqsex <- lm(rrate ~ iqfull + sex) ; summary(riqsex)
  riqsexbw <- lm(rrate ~ iqfull + sex + rbw); summary(riqsexbw)
  riqsexga <- lm(rrate ~ iqfull + sex + ga ); summary(riqsexga)
  riqsex2 <- lm(rrate ~ iqfull*sex) ; summary(riqsex2)
  rr 
  
   mrc  <- lm(iqfull ~ rcomp ) ; mrbw <- lm(iqfull ~ rbw) 
  msex <- lm(iqfull ~ sex ) ; mga <- lm(iqfull ~ ga)
   summary(mrc); summary(mrbw); summary(msex); summary(mga);  
   
   mrc2  <- lm(iqfull ~ rcomp+rbw); 
     mrc3  <- lm(iqfull ~ rcomp+rbw+sex)