Probability Distributions

Probability Distributions

R has built-in functions for common probability distributions, following a d/p/q/r naming convention -- rnorm() generates random normal values, dnorm() gives the density, pnorm() gives the cumulative probability, and qnorm() gives the quantile. This same pattern applies to other distributions like runif(), rbinom(), and rpois(). This built-in statistical machinery is a major reason R is popular for data analysis.

Note: The prefix tells you what the function does: r=random draw, d=density, p=cumulative probability, q=quantile.

Example: Probability Distributions

set.seed(1)
samples <- rnorm(5, mean = 0, sd = 1)
print(samples)

cat("P(X <= 0) for standard normal:", pnorm(0), "\n")