R script to explore the rlnorm() function

rlnorm-examples.R

# R script to explore rlnorm() 
# written by Malte Möser and Matthew Salganik
# Described in this blog post: 

set.seed(123)
draws1 <- rlnorm(n = 1000000, mean = 7, sd = 75)
mean(draws1)
sd(draws1)

draws2 <- rlnorm(n = 1000000, meanlog = log(7), sdlog = log(75))
mean(draws2)
sd(draws2)

m <- 7
s <- 75
location <- log(m^2 / sqrt(s^2 + m^2))
shape <- sqrt(log(1 + (s^2 / m^2)))
print(paste("location:", location))
print(paste("shape:", shape))
draws3 <- rlnorm(n = 1000000, location, shape)
mean(draws3)
sd(draws3)
plot(density(draws3[draws3 < 20]))