Лабораторная работа №6

data(mtcars)
head(mtcars)

##                    mpg cyl disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
## Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
## Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
## Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
## Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

set.seed(0)
library(boot)

# функция для оценки R²
rsq_function <- function(formula, data, indices) {
  d <- data[indices, ]
  fit <- lm(formula, data = d)
  return(summary(fit)$r.square)
}

# бутстрап 2000 раз
reps <- boot(data = mtcars, statistic = rsq_function, R = 2000, formula = mpg ~ disp)
reps

## 
## ORDINARY NONPARAMETRIC BOOTSTRAP
## 
## 
## Call:
## boot(data = mtcars, statistic = rsq_function, R = 2000, formula = mpg ~ 
##     disp)
## 
## 
## Bootstrap Statistics :
##      original      bias    std. error
## t1* 0.7183433 0.003272215  0.06390141

plot(reps)

boot.ci(reps, type = "bca")

## BOOTSTRAP CONFIDENCE INTERVAL CALCULATIONS
## Based on 2000 bootstrap replicates
## 
## CALL : 
## boot.ci(boot.out = reps, type = "bca")
## 
## Intervals : 
## Level       BCa          
## 95%   ( 0.5437,  0.8149 )  
## Calculations and Intervals on Original Scale