source('../../Data/data_loaders.R')

DF = load_appendix_steel_production_data()

null = lm( PROD ~ 1, data=DF )
full = lm( PROD ~ ., data=DF )

# Forward selection:
step( null, scope=list(lower=null, upper=full), direction="forward" )

# Backward selection:
step( full, direction="backward" )

# Both directions:
step( null, scope=list(upper=full), direction="both" )

# Now try the leaps package:
#
if( ! require("leaps") ){ install.packages("leaps") }
rss = regsubsets( PROD~., data=DF )
print( summary( rss ) )