library(openxlsx)

df<-read.xlsx("http://kanggc.iptime.org/book/data/consumption-e.xlsx")

year<-df[,1]
gdp<-df[,2]
consumption<-df[,3]

y<-ts(gdp, start=c(2000), frequency=1)
c<-ts(consumption, start=c(2000), frequency=1)

n<-length(y)

ny<-y[2:n]
nc<-c[2:n]
lagc<-c[1:n-1]

lm_s<-lm(c~y)
ols_s<-summary(lm_s)
ols_s
y0<-1700000
(chat_s<-summary(lm_s)$coef[1]+summary(lm_s)$coef[2]*y0)

lm_m<-lm(nc~ny+lagc)
ols_m<-summary(lm_m)
ols_m
(chat_m<-summary(lm_m)$coef[1]+summary(lm_m)$coef[2]*y0+summary(lm_m)$coef[3]*c[17])