Understanding your data begins with descriptive statistics — these provide essential summaries about the distribution, central tendency, and spread of variables. This chapter guides you through basic statistical calculations and grouped summaries using base R and dplyr.

Basic Descriptive Statistics (Base R)

The most common statistical measures are:

• Mean: average value;
• Median: middle value;
• Min / Max: smallest and largest values.

mean(df$max_power, na.rm = TRUE)      # Average max power
median(df$selling_price, na.rm = TRUE) # Median selling price
min(df$mileage, na.rm = TRUE)          # Minimum mileage
max(df$mileage, na.rm = TRUE)          # Maximum mileage
summary(df)  # Quick summary for all numeric columns

Descriptive Statistics using dplyr

Using dplyr makes calculations more readable and efficient.

df %>%
  summarise(
    avg_power = mean(max_power, na.rm = TRUE), 
    sd_power = sd(max_power, na.rm = TRUE),
    median_power = median(max_power, na.rm = TRUE)
  )