A.

library(stargazer)
## 
## Please cite as:
##  Hlavac, Marek (2022). stargazer: Well-Formatted Regression and Summary Statistics Tables.
##  R package version 5.2.3. https://CRAN.R-project.org/package=stargazer
data <- cars
stargazer(data = data, type = "text", title = "Table 1: Data Summary Statistics")
## 
## Table 1: Data Summary Statistics
## ====================================
## Statistic N   Mean  St. Dev. Min Max
## ------------------------------------
## speed     50 15.400  5.288    4  25 
## dist      50 42.980  25.769   2  120
## ------------------------------------

The dependent variable is dist (Y) and the independent variable is speed (x). The estimate equation is: \[Y \sim \beta_0 + \beta_1X + \epsilon\]

B.

lm_model <- lm(dist ~ speed, data = data)
summary(lm_model)
## 
## Call:
## lm(formula = dist ~ speed, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -29.069  -9.525  -2.272   9.215  43.201 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -17.5791     6.7584  -2.601   0.0123 *  
## speed         3.9324     0.4155   9.464 1.49e-12 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 15.38 on 48 degrees of freedom
## Multiple R-squared:  0.6511, Adjusted R-squared:  0.6438 
## F-statistic: 89.57 on 1 and 48 DF,  p-value: 1.49e-12

C.

Slope represents the change in the dependent variable for a one-unit increase in the independent variable. It indicates how much the stopping distance (‘dist’) is expected to change for each one-unit increase in speed (‘speed’).
Intercept is the value of the dependent variable when the independent variable is zero. In the ‘cars’ dataset, the intercept represents the estimated stopping distance when the speed of the car is zero.

D.

co <- cov(cars$speed, cars$dist)
vars <- var(cars$speed)
slope <- co / vars

mean_speed <- mean(cars$speed)
mean_dist <- mean(cars$dist)
intercept <- mean_dist - slope * mean_speed

cat("Slope:", slope, "\n")
## Slope: 3.932409
cat("Intercept:", intercept, "\n")
## Intercept: -17.57909