Displaying 20 results from an estimated 8000 matches similar to: "Non-Linear Regression with two Predictors"
2010 Jul 21
4
Chi-square distribution probability density function:
Hi to all I found
an formular of an **
***p-Value Calculator for the Chi-Square test*
*http://www.danielsoper.com/statcalc/calc11.aspx*
*with the formula*
*http://www.danielsoper.com/statkb/topic11.aspx*
*what's the gamma function of this formula in r?*
*df=5*
*ch2=25.50878*
*the following code does not give the result <0.001 for the values above *
*p=
2010 Nov 13
2
interpretation of coefficients in survreg AND obtaining the hazard function for an individual given a set of predictors
Dear R help list,
I am modeling some survival data with coxph and survreg (dist='weibull') using
package survival. I have 2 problems:
1) I do not understand how to interpret the regression coefficients in the
survreg output and it is not clear, for me, from ?survreg.objects how to.
Here is an example of the codes that points out my problem:
- data is stc1
- the factor is dichotomous
2010 Nov 16
1
Re : interpretation of coefficients in survreg AND obtaining the hazard function for an individual given a set of predictors
Thanks for sharing the questions and responses!
Is it possible to appreciate how much the coefficients matter in one
or the other model?
Say, using Biau's example, using coxph, as.factor(grade2 ==
"high")TRUE gives hazard ratio 1.27 (rounded).
As clinician I can grasp this HR as 27% relative increase. I can
relate with other published results.
With survreg the Weibull model gives a
2004 Feb 04
3
Various newbie questions
Hello,
1) What is the difference between a "data frame" (J H Maindonald, Using
R, p. 12) and a "vector"?
In Using R, the author asks the reader to enter the following data in a
data frame, which I will call "mydata":
year snow.cover
1970 6.5
1971 12.0
1972 14.9
1973 10.0
1974 10.7
1975 7.9
...
mydata=data.frame(year=c(1970,...),snow.cover=c(6.5,...))
2) How to
2017 Aug 26
2
DC Upgrade from 4.1.7 to 4.6.7
> -----Message d'origine-----
> De : Andrew Bartlett [mailto:abartlet at samba.org]
> Envoyé : samedi 26 août 2017 12:40
> À : HB; samba at lists.samba.org
> Objet : Re: [Samba] DC Upgrade from 4.1.7 to 4.6.7
>
> On Sat, 2017-08-26 at 12:32 +0400, HB via samba wrote:
> > >
> > Here is the output of samba-tool dbcheck :
> > # samba-tool dbcheck
>
2009 Feb 26
3
call-limit on a per destination basis
Hello,
I use asterisk to to IAX2 trunking between London POP & Reunion Island pop.
I would like to know if it's possible to do a kind of call-limit (i.e.
restrict to XX) channels but on a per dialcode and / or destination basis.
For example:
[trunk]
; reunion proper, i want to send no more than 24 channels
exten => _0262XXXXXX,1,Dial(IAX2/mytrunk/${EXTEN})
; reunion mobile, i want
2012 Nov 20
0
double gaussian with mixdist: what's wrong?
Dear all,
I am trying to fit a double gaussian to some data using the mixdist package:
--- begin code ---
? library(mixdist)
? time <- seq(673,723)
??counts <- c(3,12,8,12,18,24,39,48,64,88,101,132,198,253,331,419,563,781,1134,1423,1842,2505,374,6099,9343,13009,
? ? ? ? ? ? ? ? ? ?15097,13712,9969,6785,4742,3626,3794,4737,5494,5656,4806,3474,2165,1290,799,431,213,137,66,57,41,35,27,27,27)
?
2008 May 04
2
Ancova_non-normality of errors
Hello Helpers,
I have some problems with fitting the model for my data...
-->my Literatur says (crawley testbook)=
Non-normality of errors-->I get a banana shape Q-Q plot with opening
of banana downwards
Structure of data:
origin wt pes gender
1 wild 5.35 147.0 male
2 wild 5.90 148.0 male
3 wild 6.00 156.0 male
4 wild 7.50 157.0 male
5 wild 5.90
2003 Nov 03
1
svm in e1071 package: polynomial vs linear kernel
I am trying to understand what is the difference between linear and
polynomial kernel:
linear: u'*v
polynomial: (gamma*u'*v + coef0)^degree
It would seem that polynomial kernel with gamma = 1; coef0 = 0 and degree
= 1
should be identical to linear kernel, however it gives me significantly
different results for very simple
data set, with linear kernel
2008 Nov 19
1
F-Tests in generalized linear mixed models (GLMM)
Hi!
I would like to perform an F-Test over more than one variable within a
generalized mixed model with Gamma-distribution
and log-link function. For this purpose, I use the package mgcv.
Similar tests may be done using the function "anova", as for example in
the case of a normal
distributed response. However, if I do so, the error message
"error in eval(expr, envir, enclos) :
2011 Apr 12
1
question about optim
Dear R-users,
I would like to use optim( ) to minimize a function which depends on 4 parameters: 2 vectors, a scalar, and a matrix.
And I have a hard to define the parameters at the beginning of the function, and then to call optim. Indeed, all the examples I have seen dont treat cases where parameters are not all real.
Here is my code, it doesnt work but its just to show you where is exactly my
2011 Jun 17
2
Non-linear Regression best-fit line
I am trying to fit a curve to a cumulative mortality curve (logistic) where y is the cumulative proportion of mortalities, and t is the time in hours (see below). Asym. at 0 and 1
> y
[1] 0.00000000 0.04853859 0.08303777 0.15201970 0.40995074 0.46444992 0.62862069 0.95885057 1.00000000
[10] 1.00000000 1.00000000
> t
[1] 0 13 20 24 37 42 48 61 72 86 90
I tried to find starting values for
2011 Dec 30
1
Fwd: Re: Poisson GLM using non-integer response/predictors?
Hi,
Use offset variables if count occurrences of an event and you want to
model the
observation time.
glm(count ~ predictors + offset(log(observation_time)), family=poisson)
If you want to compare durations, look at library(survival), ?coxph
If tnoise_sqrt is the square root of tourist noise, your example seems
incorrect, because it is a predictor, not the dependent variable
tnoise_sqrt ~
2009 Oct 22
1
Automatization of non-linear regression
Hi everybody,
I'm using the method described here to make a linear regression:
http://www.apsnet.org/education/advancedplantpath/topics/Rmodules/Doc1/05_Nonlinear_regression.html
> ## Input the data that include the variables time, plant ID, and severity
> time <- c(seq(0,10),seq(0,10),seq(0,10))
> plant <- c(rep(1,11),rep(2,11),rep(3,11))
>
> ## Severity
2018 Mar 02
0
Rstmp2 - linear predictors, AICs and BICs
Dear R-help,
I am using R-3.3.2 on Windows 10. As per my previous post today, I teach on a course which has 4 computer practical sessions related to the development and validation of clinical prediction models. These are currently written for Stata and I am in the process of writing them for use in R too (as I far prefer R to Stata!)
Part of the practical requires the student to fit a flexible
2017 Aug 26
2
DC Upgrade from 4.1.7 to 4.6.7
> -----Message d'origine-----
> De : samba [mailto:samba-bounces at lists.samba.org] De la part de Rowland
> Penny via samba
> Envoyé : samedi 26 août 2017 12:00
> À : samba at lists.samba.org
> Objet : Re: [Samba] DC Upgrade from 4.1.7 to 4.6.7
>
...
> On Sat, 26 Aug 2017 11:28:00 +0400
> > Hi,
> >
> > I have begun to add a new 4.6.7 DC (following
2010 May 30
3
How can I fit a fixed-effect linear model or generalized linear model with method="ml"?
Hi,
I want to fit a linear model (without any random effect) with method "ml". I
tried to use "glm" I found that there is no option for "ml" or "reml" and
the default one is "reml". THen I tried to use "lme" but it requires a
random effect. How can I fix this problem?
Of course, it's not necessary to be "glm" or
2008 Feb 21
1
Function for linear mixed model with gamma-distributed random effects?
Hi,
I'm new to R and am hoping someone might be able to help with the following lme problem.
I am trying to fit an ellipse equation to some spatial human factors data, varying the major and minor axes randomly and specifying an exp~ variogram for errors. Using normally-distributed random effects produces some -ve minor/major axes. I am hoping to be able to specify a gamma distribution to
2008 Sep 15
1
any package to do generalized linear mixed model?
I checked GlmmML package. However, it can only do binomial and poisson
distribution. How about others such as gamma or neg binomial?
Thank you so much!
wensui
2010 Oct 27
2
coxph linear.predictors
I would like to be able to construct hazard rates (or unconditional death prob) for many subjects from a given survfit.
This will involve adjusting the ( n.event/n.risk)
with (coxph object )$linear.predictors
I must be having another silly day as I cannot reproduce the linear predictor:
fit <- coxph(Surv(futime, fustat) ~ age, data = ovarian)
fit$linear.predictors[1]
[1] 2.612756