COMMunication
RESearch.NET

library(ISLR)
attach(Carseats)
str(Carseats)
m.Sales.PriceShelveLoc <- lm(Sales ~ Price + ShelveLoc, data=Carseats)
summary(m.Sales.PriceShelveLoc)

plot(Price[ShelveLoc=="Bad"], Sales[ShelveLoc=="Bad"], 
     col="blue", xlab="Price", ylab="Sales", 
     main="Sales vs. Price, Shlv Loc")
points(Price[ShelveLoc=="Medium"], Sales[ShelveLoc=="Medium"], col="red")
points(Price[ShelveLoc=="Good"], Sales[ShelveLoc=="Good"], col="green")
legend("topright", legend=c("Good", "Medium", "Bad"), 
       col=c("green", "red", "blue"), pch=c(1,16), bty="n")

abline(a = 16.89765, b=-0.056698, col = "green", lwd=3)
abline(a = 13.86382, b=-0.056698, col = "red", lwd=3)
abline(a = 11.832984, b=-0.056698, col = "blue", lwd=3)

독립변인 간의 상호작용효과 보기

m.Sales.PriceShelveLoc.ia <- lm(Sales ~ Price + ShelveLoc + Price:ShelveLoc, data=Carseats)
summary(m.Sales.PriceShelveLoc.ia)

plot(Price[ShelveLoc=="Bad"], Sales[ShelveLoc=="Bad"], 
     col="blue", xlab="Price", ylab="Sales", 
     main="Sales vs. Price, Shlv Loc")
points(Price[ShelveLoc=="Medium"], Sales[ShelveLoc=="Medium"], col="red")
points(Price[ShelveLoc=="Good"], Sales[ShelveLoc=="Good"], col="green")
legend("topright", legend=c("Good", "Medium", "Bad"), 
       col=c("green", "red", "blue"), pch=c(1,16), bty="n")


good <- 11.832984 + 6.135880
medium <- 11.832984 + 1.630481
bad <- 11.832984

p.good <- -0.055220 + -0.010564
p.medium <- -0.055220 + 0.001984
p.bad <- -0.055220

abline(a = good, b= p.good, col = "green", lwd=3)
abline(a = medium, b= p.medium, col = "red", lwd=3)
abline(a = bad, b= p.bad, col = "blue", lwd=3)