Motor Trend Car Road Tests - Data Exploration

Author

Your Name

Published

Invalid Date

1 Introduction

This document explores the mtcars dataset, which was extracted from the 1974 Motor Trend US magazine. The dataset contains various characteristics of different car models.

2 Dataset Overview

2.1 Basic Dataset Information

Code

# Display basic information about the dataset
str(mtcars)

'data.frame':   32 obs. of  11 variables:
 $ mpg : num  21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ...
 $ cyl : num  6 6 4 6 8 6 8 4 4 6 ...
 $ disp: num  160 160 108 258 360 ...
 $ hp  : num  110 110 93 110 175 105 245 62 95 123 ...
 $ drat: num  3.9 3.9 3.85 3.08 3.15 2.76 3.21 3.69 3.92 3.92 ...
 $ wt  : num  2.62 2.88 2.32 3.21 3.44 ...
 $ qsec: num  16.5 17 18.6 19.4 17 ...
 $ vs  : num  0 0 1 1 0 1 0 1 1 1 ...
 $ am  : num  1 1 1 0 0 0 0 0 0 0 ...
 $ gear: num  4 4 4 3 3 3 3 4 4 4 ...
 $ carb: num  4 4 1 1 2 1 4 2 2 4 ...

2.2 Summary Statistics

Code

# Generate summary statistics
summary(mtcars)

      mpg             cyl             disp             hp       
 Min.   :10.40   Min.   :4.000   Min.   : 71.1   Min.   : 52.0  
 1st Qu.:15.43   1st Qu.:4.000   1st Qu.:120.8   1st Qu.: 96.5  
 Median :19.20   Median :6.000   Median :196.3   Median :123.0  
 Mean   :20.09   Mean   :6.188   Mean   :230.7   Mean   :146.7  
 3rd Qu.:22.80   3rd Qu.:8.000   3rd Qu.:326.0   3rd Qu.:180.0  
 Max.   :33.90   Max.   :8.000   Max.   :472.0   Max.   :335.0  
      drat             wt             qsec             vs        
 Min.   :2.760   Min.   :1.513   Min.   :14.50   Min.   :0.0000  
 1st Qu.:3.080   1st Qu.:2.581   1st Qu.:16.89   1st Qu.:0.0000  
 Median :3.695   Median :3.325   Median :17.71   Median :0.0000  
 Mean   :3.597   Mean   :3.217   Mean   :17.85   Mean   :0.4375  
 3rd Qu.:3.920   3rd Qu.:3.610   3rd Qu.:18.90   3rd Qu.:1.0000  
 Max.   :4.930   Max.   :5.424   Max.   :22.90   Max.   :1.0000  
       am              gear            carb      
 Min.   :0.0000   Min.   :3.000   Min.   :1.000  
 1st Qu.:0.0000   1st Qu.:3.000   1st Qu.:2.000  
 Median :0.0000   Median :4.000   Median :2.000  
 Mean   :0.4062   Mean   :3.688   Mean   :2.812  
 3rd Qu.:1.0000   3rd Qu.:4.000   3rd Qu.:4.000  
 Max.   :1.0000   Max.   :5.000   Max.   :8.000

3 Data Visualization

3.1 Miles per Gallon Distribution

Code

ggplot(mtcars, aes(x = mpg)) +
  geom_histogram(binwidth = 2, fill = "blue", color = "black") +
  labs(
    title = "Miles per Gallon Distribution",
    x = "Miles per Gallon",
    y = "Frequency"
  ) +
  theme_minimal()

3.2 Relationship between Engine Size and Fuel Efficiency

Code

ggplot(mtcars, aes(x = disp, y = mpg)) +
  geom_point(aes(color = factor(cyl)), alpha = 0.7) +
  labs(
    title = "Fuel Efficiency vs. Engine Size",
    x = "Engine Displacement (cu.in.)",
    y = "Miles per Gallon",
    color = "Cylinders"
  ) +
  theme_minimal()

Miles per Gallon vs. Engine Displacement

3.3 Transmission Type and Fuel Efficiency

Code

mtcars %>%
  mutate(am = ifelse(am == 0, "Automatic", "Manual")) %>%
  ggplot(aes(x = am, y = mpg)) +
  geom_boxplot(fill = "lightblue") +
  labs(
    title = "Fuel Efficiency by Transmission Type",
    x = "Transmission Type",
    y = "Miles per Gallon"
  ) +
  theme_minimal()

4 Statistical Analysis

4.1 Correlation Matrix

Code

# Create correlation matrix
correlation_matrix <- cor(mtcars)
corrplot::corrplot(correlation_matrix, method = "color")

4.2 T-Test: Transmission Type and MPG

Code

# Perform t-test to compare MPG between transmission types
t_test_result <- t.test(mpg ~ am, data = mtcars)