Bioequivalence and Bioavailability Forum • parametrization of R function rlnorm

parametrization of R function rlnorm [🇷 for BE/BA]

posted by martin – Austria, 2010-05-02 20:22 (5474 d 00:13 ago) – Posting: # 5272
Views: 58,590

dear d_labes!

I just want to draw your attention to the parametrization of R function rlnorm. When you want to generate log-normal distributed random variables with a given mean and CV on the observed scale - I suggest to use meanlog=log(mean)-0.5*log(1+cv^2) instead of meanlog=log(mean).

# example

set.seed(020510)

n <- 1E6

mue <- 5

cv <- 0.5



x <- rlnorm(n=n, meanlog=log(mue)-0.5*log(1+cv^2), sdlog=sqrt(log(1+cv^2)))

y <- rlnorm(n=n, meanlog=log(mue), sdlog=sqrt(log(1+cv^2)))



mean(x); sd(x)/mean(x)

mean(y); sd(y)/mean(y)

best regards

martin

Complete thread:

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