[R] [FORGED] qqPlot vs qqcomp

peter dalgaard pdalgd at gmail.com
Tue Dec 22 19:38:39 CET 2015

> On 22 Dec 2015, at 07:30 , mohsen hs via R-help <r-help at r-project.org> wrote:
> The above command gives me a differentplot. I am not sure what part I am doing wrong. I appreciate your time forconsidering my request and your feedback is highly appreciated. Please find the plots attached. The right one is from qqcomp and the left one is from qqPlot. Titles might be incorrect.

They never arrived, but your data weren't actually needed. The crucial missing information was the packages used. This will do:

> library(EnvStats); library(fitdistrplus)
> serving <- exp(rnorm(100))
> qqPlot ( serving, dist ="lnorm", estimate.params = TRUE, add.line = TRUE)
> fitln <- fitdist(serving,"lnorm",method="mle")
> qqcomp(fitln)

The difference is quite clearly that qqPlot is doing a QQ-plot of log(serving) vs. normal quantiles, whereas qqcomp plots serving itself against lognormal quantiles. So the former is pretty much equal to the latter on a log-log scale.

Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

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