#                                                                     
# 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

# The largest and smallest model we would consider (all possible variables):
# 
m_Largest = glm( chd ~ sbp + tobacco + ldl + famhist + obesity + alcohol + age, family=binomial(), data=SAheart )
m_Smallest = glm( chd ~ 1.0, family=binomial(), data=SAheart )

stepped_model = step( m_Largest, scope=list(lower=~+1, upper=~sbp + tobacco + ldl + famhist + obesity + alcohol + age), direction="backward", data=SAheart )

print( stepped_model )