Displaying 20 results from an estimated 1000 matches similar to: "test for exponential,lognormal and gammadistribution"
2005 Sep 12
1
fit data with gammadistribution
hello
my data is
data2:2743 4678 21427 6194 10286 1505 12811 2161 6853 2625 14542 694
11491 14924 28640 17097 2136 5308 3477 91301 11488 3860 64114 14334
by calculating
shape<-(mean(data2))^2/var(data2)
scale<-var(data2)/mean(data2)
i get the idea what the parameters of the gammadistribution would be.
but if i try using the method mle() i get stock and i don't know, how to
2005 Dec 03
1
Fit Frechet Distribution
hello everybody
i want to use the maximum likelihood method to estimate FRECHET parameters of
my sample data.
Should it work with fitdistr in the package MASS?
I only find how to do it for GEV, Gumbel, and almost all other distributions,
but FRECHET?
I would be very happy if somebody can tell me how to do fit the FRECHET
distribution!
Thanks
Nadja Riedwyl
2005 Jan 11
3
Kolmogorov-Smirnof test for lognormal distribution with estimated parameters
Hello all,
Would somebody be kind enough to show me how to do a KS test in R for a
lognormal distribution with ESTIMATED parameters. The R function
ks.test()says "the parameters specified must be prespecified and not
estimated from the data" Is there a way to correct this when one uses
estimated data?
Regards,
Kwabena.
--------------------------------------------
Kwabena Adusei-Poku
2005 Sep 06
2
(no subject)
my problem actually arised with fitting the data to the weibulldistribution,
where it is hard to see, if the proposed parameterestimates make sense.
data1:2743;4678;21427;6194;10286;1505;12811;2161;6853;2625;14542;694;11491;
?? ?? ?? ?? ?? 14924;28640;17097;2136;5308;3477;91301;11488;3860;64114;14334
how am I supposed to know what starting values i have to take?
i get different
2005 Sep 06
2
fitting distributions with R
Dear all
I've got the dataset
data:2743;4678;21427;6194;10286;1505;12811;2161;6853;2625;14542;694;11491;
?? ?? ?? ?? ?? 14924;28640;17097;2136;5308;3477;91301;11488;3860;64114;14334
I know from other testing that it should be possible to fit the data with the
exponentialdistribution. I tried to get parameterestimates for the
exponentialdistribution with R, but as the values
of the parameter
2008 Oct 07
3
Fitting weibull, exponential and lognormal distributions to left-truncated data.
Dear All,
I have two questions regarding distribution fitting.
I have several datasets, all left-truncated at x=1, that I am attempting
to fit distributions to (lognormal, weibull and exponential). I had
been using fitdistr in the MASS package as follows:
fitdistr<-(x,"weibull")
However, this does not take into consideration the truncation at x=1. I
read another posting in this
2004 Mar 19
3
Incomplete Gamma Functions and GammaDistribution Doc errata.
Hello all,
In the course of trying to implement the CDF of an
InverseGammaDistribution, I have run across the need for an igamma()
function. Several others have needed this function but the answers I
have found so far are not totally clear to me. I'm writing for three
reasons:
1) to present a small error in the docs
2) to clarify the approach we are expected to take
3) to request,for the
2005 Mar 18
1
Pb with ks.test pvalue
Hello,
While doing test of normality under R and SAS, in order to prove the efficiency of R to my company, I notice
that Anderson Darling, Cramer Van Mises and Shapiro-Wilk tests results are quite the same under the two environnements,
but the Kolmogorov-smirnov p-value really is different.
Here is what I do:
> ks.test(w,pnorm,mean(w),sd(w))
One-sample Kolmogorov-Smirnov test
data: w
D
2005 Jun 27
1
ks.test() output interpretation
I'm using ks.test() to compare two different
measurement methods. I don't really know how to
interpret the output in the absence of critical value
table of the D statistic. I guess I could use the
p-value when available. But I also get the message
"cannot compute correct p-values with ties ..." does
it mean I can't use ks.test() for these data or I can
still use the D
2006 Jul 09
1
KS Test Warning Message
All,
Happy World Cup and Wimbledon. This morning finds me with the first
of my many daily questions.
I am running a ks.test on residuals obtained from a regression model.
I use this code:
> ks.test(Year5.lm$residuals,pnorm)
and obtain this output
One-sample Kolmogorov-Smirnov test
data: Year5.lm$residuals
D = 0.7196, p-value < 2.2e-16
alternative hypothesis: two.sided
Warning
2003 Nov 05
1
Fitting a 3-parameter gammadistribution
I have 'grouped' data, that is in the form of:
Interval Median
0-9.9%: -25
10-19.9%: 0
20-29.9%: 3
30-39.9%: 10
40-49.9%: 50
50-59.9%: 200
et cetera
and want to fit a three parameter gamma distribution. Does anyone know of an existing routine for doing this (or something similar)? Any help or comment is much appreciated.
Regards,
M?rten
M?rten
2024 Apr 15
2
Synthetic Control Method
Good Morning
I want to perform a synthetic control method with R. For this purpose, I
created the following code:
# Re-load packages
library(Synth)
library(readxl)
# Pfadeinstellung Excel-Blatt
excel_file_path <-
("C:\\Users\\xxxxx\\Desktop\\DATA_INVESTMENTVOLUMEN_FOR_R_WITHOUT_NA.xlsx")
# Load the Excel file
INVESTMENTVOLUME <- read_excel(excel_file_path)
#
2006 Jan 20
3
domU Device eth0 does not seem to be present
I can''t find network device in domU.
Debian domU shows
Configuring network interfaces...SIOCSIFADDR: No such device
eth0: ERROR while getting interface flags: No such device
and Fedora domU shows:
eth0: unknown interface: No such device
Dom0 is using Fedora with:
kernel-xen-guest.i686 2.6.15-1.29_FC5 installed
kernel-xen-hypervisor.i686
2006 Mar 15
2
difftime arguments
Hi
I just started using RGui.exe under widnows.
I have a text file containing date arranged in columns and rows, each column has the same format, each row with different formats. 3 of the columns are something like this 1/12/2006 3:59:45 PM
I need to calculate the different in seconds between 2 selected periods using their row’s index
My solution:
Read the file in a data frame and
2009 May 29
1
Mean of lognormal in base-2
Hi, Does anyone know what the mean value of a lognormal distribution in base-2 is? I am simulating stochastic population growth and if I were working in base-e, I would do:lambda <- 1.1 #multiplicative growth rates <- 0.6 #stochasticity (std. dev)lognormal <- rlnorm(100000, log(lambda) - (s^2)/2, s)## or lognormal <- exp( rnorm( 100000, log(lambda) - (s^2)/2,
2005 Jan 17
1
merge data frames taking mean/mode of multiple macthes
Hello :)
I have two data frames, one has properties taken on a
piece by piece basis and the other has performance on
a lot by lot basis. I wish to combine these two data
frames but the problem is that each lot has multiple
pieces and hence i need to take a mean of the
properties of multiple pieces and match it to the row
having data about the lot.
I was wondering if there is a simple commmand,
2007 Sep 07
1
How to obtain parameters of a mixture model of two lognormal distributions
Dear List,
I have read that a lognormal mixture model having a pdf of the form
f(x)=w1*f1(x)+(1-w1)*f2(x) fits most data sets quite well, where f1
and f2 are lognormal distributions.
Any pointers on how to create a function that would produce the 5
parameters of f(x) would be greatly appreciated.
> version
_
platform i386-pc-mingw32
arch i386
os
2006 Aug 05
1
AIC for lognormal model
Dear all,
I want to compare some different models for a dataset by QQ plots and AIC. I get the following AICs:
- linear model: 19759.66
- GAMLSS model: 18702.7
- linear model with lognormal response: -7862.182
The QQ plots show that the lognormal model fits better than the linear model, but still much worse than the GAMLSS. So, in my opinion, the AIC of the lognormal model should be between the
2007 Mar 23
1
generating lognormal variables with given correlation
Dear R users
I use simulated data to evaluate a model by sampling the parameters in
my model from lognormal distributions.
I would like these (lognormal distributed) parameters to be correlated,
that is, I would like to have pairwise samples of 2 parameters with a
given correlation coefficient.
I have seen that a covariance matrix can be fixed when generating random
variables from a
2010 Dec 27
3
Gamma & Lognormal Model
Dear,
I'm very new to R Gui and I have to make an assignment on Gamma Regressions.
Surfing on the web doesn't help me very much so i hope this forum may be a
step forward.
The question sounds as follows:
The data set is in the library MASS
first install library(MASS)
then type data(mammals)
attach(mammals)
Assignment:
Fit the gamma model and lognormal model for the mammals data.