#                                                                     
# Written by:                                                         
# --                                                                  
# John L. Weatherwax                2009-04-21                        
#                                                                     
# email: wax@alum.mit.edu                                             
#                                                                     
# Please send comments and especially bug reports to the              
# above email address.                                                
#                                                                     
#-----                                                                

library(ElemStatLearn) # loads the data frame SAheart
library(splines)

# Computes the logistic regression model using natural splines (note famhist is included as a factor): 
form = "chd ~ ns(sbp,df=4) + ns(tobacco,df=4) + ns(ldl,df=4) + famhist + ns(obesity,df=4) + ns(alcohol,df=4) + ns(age,df=4)"
form = formula(form)

m = glm( form, data=SAheart, family=binomial )
print( summary(m), digits=3 )

# Duplicates the numbers from Table 5.1:
# 
drop1( m, scope=form, test="Chisq" )