HW21 Log

> kyph = read.table("kyphosis.dat",header=T)
> dim(kyph)
[1] 81  5
> names(kyph)
[1] "Id"       "Kyphosis" "Age"      "Number"   "Start"   

> glmstep = step(glm(Kyphosis ~ Age, data=kyph, family=binomial),
+    Kyphosis ~ (Age + Number)*Start, direction="both")
Start:  AIC= 85.93 
 Kyphosis ~ Age 

         Df Deviance    AIC
+ Start   1   65.299 71.299
+ Number  1   71.627 77.627
- Age     1   83.234 85.234
<none>        81.932 85.932

Step:  AIC= 71.3 
 Kyphosis ~ Age + Start 

            Df Deviance    AIC
+ Number     1   61.380 69.380
<none>           65.299 71.299
- Age        1   68.072 72.072
+ Age:Start  1   64.336 72.336
- Start      1   81.932 85.932

Step:  AIC= 69.38 
 Kyphosis ~ Age + Start + Number 

               Df Deviance    AIC
<none>              61.380 69.380
+ Age:Start     1   60.443 70.443
- Age           1   64.536 70.536
+ Number:Start  1   60.992 70.992
- Number        1   65.299 71.299
- Start         1   71.627 77.627


> table(trunc(5*glmup$fit),kyph$Kyphosis)
   
    absent present
  0     51       2
  1      7       5
  2      3       5
  3      2       3
  4      1       2