library("AER")
library("ggplot2")
library("dplyr")

data("CigarettesSW")
h <- CigarettesSW
glimpse(h)
help("CigarettesSW")

h2 <- filter(h, year=="1995")
glimpse(h2)

# a <- 7
# a == 9

h3 <- mutate(h2, rprice = price/cpi, rtax = tax/cpi,
rtaxs = taxs/cpi, rincome = income/population/cpi)

glimpse(h3)

# МНК

model_0 <- lm(log(packs)~log(rprice), data=h3)
summary(model_0)

# Двухшаговый МНК

# Шаг 1
step_1 <- lm(data=h3, log(rprice)~rtax)
fitted(step_1) # прогнозы
coef(step_1) # оценки коэффициентов
resid(step_1) # остатки

h3$hat_log_p <- fitted(step_1)
glimpse(h3)

# Шаг 2
step_2 <- lm(data=h3, log(packs)~hat_log_p)
summary(step_2)