# 3. feladat
pontok = read.table("adat3B.txt",header=TRUE)
pontok
attach(pontok)
plot(x,y)
reg1 = lm(y ~ x)
reg1
abline(coef(reg1),col="blue")
reg2 = lm(y ~ x + I(x^2))
reg2
lines(x,fitted(reg2),col="red")
plot(x,resid(reg2))
plot(fitted(reg2),resid(reg2))
summary(reg2)
# x-hez p-value ~ 0.7, elhagyhato
reg3 = update(reg2, .~.-x) # vagy reg3 = lm(y ~ I(x^2))
plot(x,y)
lines(x,fitted(reg3),col="purple")
anova(reg1,reg2)
anova(reg3,reg2)