Displaying 20 results from an estimated 4000 matches similar to: "Standard Error"
2011 Nov 17
2
RV: Reporting a conflict between ADMB and Rtools on Windows systems
De: Rubén Roa
Enviado el: jueves, 17 de noviembre de 2011 9:53
Para: 'Users@admb-project.org'
Asunto: Reporting a conflict between ADMB and Rtools on Windows systems
Hi,
I have to work under Windows, it's a company policy.
I've just found that there is a conflict between tools used to build R packages (Rtools) and ADMB due to the need to put Rtools compiler's
2008 Feb 18
0
Solved (??) Behaviour of integrate (was 'Poisson-lognormal probab ility calculations')
Hi Again,
I think I've solved my problem, but please tell me if you think I'm wrong,
or you can see a better way!
A plot of the integrand showed a very sharp peak, so I was running into the
integrand "feature" mentioned in the note. I resolved it by limiting the
range of integration as shown here:
--------------------------------------------------
function (x, meanlog = 0,
2007 Feb 14
0
How to use Rpad
I am a beginner and I don't know how to use Rpad package.
I installed it and opened the following example .Rpad page in Internet
Explorer.
When I clicked "Calculate" button, nothing seems to happen. Can anyone tell
me how to use Rpad?
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
<html>
<!-- by Tom Short, EPRI, tshort at epri.com
(c) Copyright 2005 by
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,
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
2011 Nov 01
1
low sigma in lognormal fit of gamlss
Hi,
I'm playing around with gamlss and don't entirely understand the sigma
result from an attempted lognormal fit.
In the example below, I've created lognormal data with mu=10 and sigma=2.
When I try a gamlss fit, I get an estimated mu=9.947 and sigma=0.69
The mu estimate seems in the ballpark, but sigma is very low. I get similar
results on repeated trials and with Normal and
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
2008 Jul 17
0
How to compute loglikelihood of Lognormal distribution
Hi,
I am trying to learn lognormal mixture models with EM.
I was wondering how does one compute the log likelihood.
The current implementation I have is as follows,
which perform really bad in learning the mixture models.
__BEGIN__
# compute probably density of lognormal.
dens <- function(lambda, theta, k){
temp<-NULL
meanl=theta[1:k]
sdl=theta[(k+1):(2*k)]
2008 Feb 22
1
fitting a lognormal distribution using cumulative probabilities
Dear all,
I'm trying to estimate the parameters of a lognormal distribution fitted
from some data.
The tricky thing is that my data represent the time at which I recorded
certain events. However, in many cases I don't really know when the event
happened. I' only know the time at which I recorded it as already happened.
Therefore I want to fit the lognormal from the cumulative
2011 Jul 10
1
Chebyshev Inequality — MVUE
Hello,
I was interested in trying to write an R script to calculate a UCL for a lognormal distribution using the Chebyshev Inequality — MVUE Approach (based on EPA’s guidance found in http://www.epa.gov/oswer/riskassessment/pdf/ucl.pdf). This looks like it should be straight forward, but I am need to calculate an MVUE for the population mean and an MVUE for the population variance, which requires
2008 Feb 15
0
tests of lognormal distribution
Hi all,
I have a data of lognormal distribution (sample size > 1,000,000).
What I want to do is
1) to test if my dataset is a lognormal distribution or not (Histogram shows
a nice normal distribution in log scale but I want to check)
2) two subsets from this dataset have same mean or not (like "t test" of
normal distribution)
What I tried are
1) ad.test{truncgof} of R, which is a
2011 Aug 26
2
How to generate a random variate that is correlated with a given right-censored random variate?
Hi,
I have a right-censored (positive) random variable (e.g. failure times subject to right censoring) that is observed for N subjects: Y_i, I = 1, 2, ..., N. Note that Y_i = min(T_i, C_i), where T_i is the true failure time and C_i is the censored time. Let us assume that C_i is independent of T_i. Now, I would like to generate another random variable U_i, I = 1, 2, ..., N, which is
2001 Nov 14
0
Fitting Pareto dist in a mixture
Dear all:
First, apologies for cross-posting multiplicities and for a query that is
more
analytically related than S-language related.
The bottom-line wish is:
Could you please provide and advice, references, etc on S software
approaches for
fitting a distribution with density:
p*g(x) + (1-p)*f(x)
where g(x) is the familiar lognormal 2-parameter density
and f(x) is Pareto as defined below?
2003 Feb 27
2
interval-censored data in survreg()
I am trying to fit a lognormal distribution on interval-censored
data. Some of my intervals have a lower bound of zero.
Unfortunately, it seems like survreg() cannot deal with lower
bounds of zero, despite the fact that plnorm(0)==0 and
pnorm(-Inf)==0 are well defined. Below is a short example to
reproduce the problem.
Does anyone know why survreg() must behave that way?
Is there an alternate
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
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.
2010 Aug 01
2
Lognormal distribution - Range Factor
Hi, What does it mean to say Lognormal distribution with a mean of 1.03E-6
with a range factor of 100 ? How can I find the lognormal distribution
paramters from this information?
Thanks, Tims
[[alternative HTML version deleted]]
2008 May 04
1
Is my understanding of rlnorm correct?
rlnorm takes two 'shaping' parameters: meanlog and sdlog.
meanlog would appear from the documentation to be the log of the mean.
eg if the desired mean is 1 then meanlog=0.
So to generate random values that fit a lognormal distribution I would
do this:
rlnorm(N , meanlog = log(mean) , sdlog = log(sd))
But when I check the mean I don't get it when sdlog>0. Interestingly I
2010 Mar 26
1
Poisson Lognormal
Hi R Users,
I'm going to estimate via. ML the parameters in Poisson Lognormal
model. The model is:
x | lambda ~ Poisson(lambda)
lambda ~ Lognormal(a,b)
Unfortunately, I haven't found a useful package allowing for such
estimation. I tried to use "poilog" package, but there is no equations
and it's hard to understand what exactly this package really does.
Using it I get the
2002 Dec 10
1
Lognormal distribution
I am trying to fit a lognormal distribution to a set of data and test its
goodness of fit with regard to predicted values.
I managed to get so far:
> y <- c(2,6,2,3,6,7,6,10,11,6,12,9,15,11,15,8,9,12,6,5)
> library(MASS)
> fitdistr(y,"lognormal",start=list(meanlog=0.1,sdlog=0.1))
meanlog sdlog
1.94810515 0.57091032
(0.12765945) (0.09034437)
But I would