Displaying 20 results from an estimated 20000 matches similar to: "Double Sided Box-Cox models?"
2006 Apr 13
3
Penalized Splines as BLUPs using lmer?
Dear R-list,
I?m trying to use the lmer of the lme4 package to fit a linear mixed model
of the form
Y = Xb + Zu + e
and I can?t figure out how to control the covariance structure of u. I want
u ~ N(0,sigma^2*I).
More precisely I?m trying to smooth a curve through data using the
"Penalized Splines as BLUPs" method as described in Ruppert, Wand &
Carroll (2003).
So I have Z = [Z1
2012 Feb 07
2
box.cox
Hello
I am using box.cox() and I get this error message:
Warning message:
'box.cox' is deprecated.
Use 'bcPower' instead.
See help("Deprecated") and help("car-deprecated").
I went to help but I did not understand the explanation, I am still wondering what is really happening.
Thanks
/R
2008 Feb 06
1
box.Cox.powers() warning
Dear Rlist,
Using an example in box.cox.powers() help, I have the following warning message.
example:
library(car)
>attach(Prestige)
> box.cox.powers(income)
Box-Cox Transformation to Normality
Est.Power Std.Err. Wald(Power=0) Wald(Power=1)
0.1793 0.1108 1.6179 -7.4062
L.R. test, power = 0: 2.7103 df = 1 p = 0.0997
L.R. test, power = 1: 47.261 df = 1 p = 0
2011 May 04
2
Box-Cox transformation in R
Hi,
Could any one please help how I can transform data based on Box-Cox Transformations in R.
Any helps will be much appreciated.
thanks,
Kagba
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2006 Feb 09
3
about Cox-Box transformation
Dear R-users,
I am using R version 1.8.0-1 under Suse 8.2.
I need to use the boxcox command because I want to apply a Cox-Box
transformation to a vector of rainfall values.
Within the libraries, the MASS library is present, but I don't know
whether this means that is automatically installed or not.
The command doesn't work. What do I have to do in order to make it
working? Is just a
2010 Jan 11
3
Problem about Box-Cox transformation (topic in html form)
Hi:
Recently, I want to perform a transformation on my data to make it more
normal, meanwhile the order statistics is unchanged. So I decided to use a
box-cox transformation.
below is the qq-plot of the original data
http://n4.nabble.com/file/n1011015/start%2Bvalue%2Bproblem%2B02.jpeg
Note that the min of my data is -1099, so I add a fix value 1200 to the
original sample.
I choose the
2010 May 16
2
Box-Cox Transformation: Drastic differences when varying added constants
Dear experts,
I tried to learn about Box-Cox-transformation but found the following thing:
When I had to add a constant to make all values of the original variable
positive, I found that
the lambda estimates (box.cox.powers-function) differed dramatically
depending on the specific constant chosen.
In addition, the correlation between the transformed variable and the
original were not 1 (as I
2003 Jun 24
2
Haw I get best lambda in box-cox
Hi all,
Does anyone know of a function that return the best lambda in box-cox
transformation?
many thanks for any help.
--
Cristiane S. Rocha
Laboratorio Genoma Funcional - Bioinform?tica
Centro de Biologia Molecular e Engenharia Genetica
Universidade Estadual de Campinas
Campinas - SP - Brasil
Tel:(19)3788-1119
2003 Nov 20
3
nls, nlrq, and box-cox transformation
Dear r-help members
I posted this message already yesterday, but don't know whether it
reached you since I joined the group only yesterday.
I would like to estimate the boxcox transformed model
(y^t - 1)/t ~ b0 + b1 * x.
Unfortunately, R returns with an error message when I try to
perform this with the call
nls( I((y^t - 1)/t) ~ I(b0 + b1*x),
start = c(t=1,b0=0,b1=0), data = mydataframe)
2007 Jan 22
1
Finding the effect of Box-Cox transformation using "vis.boxcoxu"
Dear all R users,
I have a dataset 'data' and I want to see the effect of Box-Cox
transformation on it Interactively for different lambda values. I already
got a look on function "vis.boxcoxu" in package "TeachingDemos". But I
didn't find any option to put user's own dataset. Can anyone tell me how to
put my own dataset here i.e. "data"?
Thanks and
2003 Jun 11
1
COX PH models for event histories?
This is a question about the use of the Cox proportional hazards model to analyze event histories.
I am looking at the responses of sympathetic nervous system activity to a stimulus. The activity I observe is a burst that can only occur once per heart beat cycle (e.g., a binary count). Typically bursts occur in 60-80% of the heart cycles * sensory stimuli can modify these burst probabilities.
2005 Jan 25
1
Box-Cox / data transformation question
Dear R users,
Is it reasonable to transform data (measurements of plant height) to the
power of 1/4? I?ve used boxcox(response~A*B) and lambda was close to 0.25.
Regards,
Christoph
2004 Dec 20
1
why use profile likelihood for Box Cox transformation?
Hi All,
I'm analysing some data that is conventionally modelled as log(Y) = a + bX + e. However, using the boxcox function, it appears that the optimum value of lambda is approx 0.05. I have 40 data sets of differing sizes and for about half of these, lambda is significantly non-zero. So, it is worth looking into.
The alternative model, Y^lambda = a + bX + e, has been explored before by
2009 May 19
4
nlrwr package. Error when fitting the optimal Box-Cox transformation with two variables
Dear all:
I'm trying to fit the optimal Box-Cox
transformation related to nls (see the code
below) for the demand of money data in Green (3th
Edition) but in the last step R gives the next
error message.
Error en
`[.data.frame`(eval(object$data), ,
as.character(formula(object)[[2]])[2]) :
undefined columns selected.
?Any idea to solve the problem?
Thanks in advance,
2005 Nov 06
2
cox models
Hello,
i'm a french student of medical oncology and i'm working on breast
cancer. I have a variable with the histologic type of tumor wich is
between 1 and 5. I use as.factor function to make some variable with
level between 1 and 5. When i put it in the cox model i have only the
level between 2 and 5. The level 1 doesn't appear. I think i have to
change the number of level but i
2006 Sep 03
2
Running cox models
Hi,
I'm reading van Belle et al "Biostatistics" and trying to run a cox test using
a dataset from:
http://faculty.washington.edu/~heagerty/Books/Biostatistics/chapter16.html
(Primary Biliary Cirrhosis data link at top of the page),
I'm using the following code:
--------------- start of code
library(survival)
liver <-
2012 Jul 13
2
Power analysis for Cox regression with a time-varying covariate
Hello All,
Does anyone know where I can find information about how to do a power analysis for Cox regression with a time-varying covariate using R or some other readily available software? I've done some searching online but haven't found anything.
Thanks,
Paul
2009 Feb 20
1
Diagnostics for single-observation deletion in Cox models
Hi,
Storer and Crowley (JASA 1985) presented an approach for approximating the
changes in maximum partial-likelihood parameter estimates for the Cox model
when a single observation is deleted. Is there an R implementation of this
approach?
Any help is greatly appreciated. Thanks.
Best,
Ravi.
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Ravi
2009 Mar 05
1
programing for partial maximum likelihood for cox models with two covariate
dears,
I like two write a program with R to estimate the coefficients of covariate,I like two know the original program for this programing for partial maximum likelihood for cox models with two co variate.
I did it with coxph command,
thanks
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2017 Nov 01
3
Cox Regression : Spline Coefficient Interpretation?
Hi,
I'm using a Cox-Regression to estimate hazard rates on prepayments.
I'm using the "pspline" function to face non-linearity, but I have no clue
how to interpret the result.
Unfortunately I did not find enough information on the "pspline" function
wether in the survival package nor using google..
I got following output:
* library(survival)*
>
>
>
>