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 (5881 d 17:34 ago) – Posting: # 5272
Views: 68,423

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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    - Parallel groups in bear - CIs ElMaestro 2010-04-22 21:47
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        WNL in replicate BE yjlee168 2010-04-26 08:59
        
        WNL in replicate BE Helmut 2010-04-26 16:15
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        Modelling Parallel bears ElMaestro 2010-04-25 20:40
        Dataset Helmut 2010-04-25 22:38
        
        Dataset yjlee168 2010-04-25 22:44
        
        Dataset Helmut 2010-04-26 01:13
        
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        Equal variances d_labes 2010-04-26 09:04
        
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        GLM = Equal variances d_labes 2010-04-26 13:29
        
        GLM = Equal variances Helmut 2010-04-26 14:45
        
        I'm a believer d_labes 2010-04-26 15:58
        
        I'm a believer Helmut 2010-04-26 16:31
        
        Equal variances Helmut 2010-04-26 12:55
        
        gls() for unequal variances? d_labes 2010-04-26 16:36
        
        gls() for unequal variances? Helmut 2010-04-26 17:00
        Sims Helmut 2010-04-27 01:36
        
        Sandwich - Simsalabim d_labes 2010-04-28 10:58
        
        Sandwich - Simsalabim Helmut 2010-04-28 14:19
        parametrization of R function rlnormmartin 2010-05-02 18:22
        
        Mean of log-normal d_labes 2010-05-03 16:22
        parametrization of R function rlnorm ElMaestro 2013-07-26 21:42
        
        Martin‽ Helmut 2013-07-28 02:01