[R] Gamma Distribution - is there any problem with "pgamma"?
Martyn Byng
martyn.byng at nag.co.uk
Wed Mar 11 12:48:47 CET 2015
Hi,
Try
pgamma(amounts,shape_gamma,scale=scale_gamma)
as I am guessing you mean scale_gamma to be the scale of the distribution, but are using it as the rate ( = 1 / scale) instead
Martyn
-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Amelia Marsh
Sent: 11 March 2015 09:42
To: r-help at r-project.org
Subject: [R] Gamma Distribution - is there any problem with "pgamma"?
Dear R forum
I have following data
amounts = c(928906.144,156091.0576,433798.3404,993425.7224,1323976.364,649106.9339, 369967.2612,2528872.35,1226093.655,1145446.149,1809624.453,599329.0394,2200955.213,2583318.064,745625.8069,961828.8828,1744841.313,1939390.005,1077873.654,729924.2713,803584.2636,287020.8529,530910.9004,818574.0089,1908133.51,262336.0893,593808.2542,780258.1354)
# Estimating Gamma distribution parameters
shape_gamma <- (mean(amounts)/sd(amounts))^2
scale_gamma <- (sd(amounts)^2/mean(amounts))
Fx <- pgamma(amounts, shape_gamma, scale_gamma)
I get following values of Fx
> Fx
[1] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
I have tried this for different dataset but still each time I am getting values of Fx as 1's only.
Is there any problem with pgamma command?
Kindly advise.
Regards
Amelia
______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
________________________________________________________________________
This e-mail has been scanned for all viruses by Star.\ _...{{dropped:3}}
More information about the R-help
mailing list