setwd("/Users/hlopes/Desktop/TEACHING/2016-2to6-Econometria-graduacaoeconomia/aulas/aula0323") houses <-read.table("http://hedibert.org/wp-content/uploads/2014/03/houseprices.txt",header=TRUE) attach(houses) n = nrow(houses) # Variavel dependente: preco # Variavel explicativa: area # Analise comparativa da Nbhd=3 vs Nbhd={1,2} # ------------------------------------------- nbhd3 = rep(0,n) nbhd3[Nbhd==3]=1 plot(SqFt,Price,col=1+nbhd3,pch=16) reg.Nbhd1 = lm(Price[nbhd3==0]~SqFt[nbhd3==0]) reg.Nbhd2 = lm(Price[nbhd3==1]~SqFt[nbhd3==1]) abline(reg.Nbhd1$coef,col=1,lwd=2) abline(reg.Nbhd2$coef,col=2,lwd=2) summary(reg.Nbhd1) summary(reg.Nbhd2) # Nossa primeira regressao com variavel dummy/binaria summary(lm(Price~SqFt+nbhd3)