xy = read.table("data030102.txt")

X1 = xy$V1;
X2 = xy$V2;
X3 = xy$V3;
X4 = xy$V4;
X5 = xy$V5;
X6 = xy$V6;
X7 = xy$V7;
X8 = xy$V8;

Y = xy$V10;
n = length(Y)


Base = lm(Y ~ 1)
Full = lm(Y~X1+X2+X3+X4+X5+X6+X7+X8)

# Forward selection
step(Base, scope = list(upper=Full, lower=~1), direction = "forward", trace=TRUE)


# Backward selection
step(Full, scope = list(upper=Full, lower=~1), direction = "backward", trace=TRUE)

# Stepwise selection
step(Full, scope = list(upper=Full, lower=~1), direction = "both", trace=TRUE)

# BIC
step(Full,   direction = "both",  k = log(n))

# AIC
step(Full,   direction = "both",  k = 2)