Displaying 20 results from an estimated 30000 matches similar to: "linear model: Test difference between coefficients and given values (t.test?)"
2009 Jul 20
1
package lmodel2: p-value RMA fitting?
Hi *,
is there a way to obtain some kind of p-value for a model fitted with RMA
using the lmodel2 package?
I know that p-values are discussed and criticized a lot and as you can image
from my question I'm not
very much of a statistican (only writing my bachelor thesis).
As fare as I understood the confidence interval statistic correctly, a
coefficient is regarded as statistically
significant
2010 Nov 17
2
Problem with plotting diagnostics - Error in object$coefficients : $ operator is invalid for atomic vectors
hi all,
after fitting a multiple linear regression
model <- lm(y ~ a + b+ c+d)
i wanted to plot diagnostics
plot(model)
but get the error message
Error in object$coefficients : $ operator is invalid for atomic vectors.
which does not make a lot of sense, since there is no "$" - i am working with an attached dataset.
can anyone help, please??
thanks a lot,
kat
2005 Mar 18
4
Sweave/margin
Hi!
I am currently using Sweave for writing my bachelor thesis - and I have a
problem:
I am using a LaTeX style (report) with quite big margin spaces. The Sweave
generated LaTeX code "floats" into the margin - and it looks ugly. The text
is blocked and fine... then there comes some flattering code running over
the margin... and blocked text again.
Considering the LaTeX output, I guess
2012 Nov 25
3
Comparing linear regression coefficients to a slope of 1
Hi!
I have a question that is probably very basic, but I cannot figure out how
to do it. I simply need to compare the significance of a regression slope
against a slope of 1, instead of the default of zero.
I know this topic has been posted before, and I have tried to use the
advice given to others to fix my problem. I tried the offset command based
on one of these advice threads as follows:
2016 Apr 26
0
Linear Regressions with constraint coefficients
Have you tried web searching on " R constrained linear regression" or
similar. There seemed to be resources related to your issues when I
looked. You might also search on rseek.org . There are apparently
several packages that do regression with constraints, but I don't know
if they fit your situation.
Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that
2016 Apr 26
1
Linear Regressions with constraint coefficients
If the slope coefficients sum to a constant, the regressors are
dependent and so a unique solution is impossible (an infinity of
solutions would result). So I think you have something going on that
you don't understand and should consult a local statistician to help
you formulate your problem appropriately.
Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that people
2016 Apr 26
2
Linear Regressions with constraint coefficients
Ok, and if I would just like to force my slope coefficients to be inside an interval, let's say, between 0 and 1? Is there a way in R to formulate such a constraint regression?
Thanks in advance and kind regards,
Aljosa
Aljosa Aleksandrovic, FRM, CAIA
Quantitative Analyst - Convertibles
aljosa.aleksandrovic at man.com
Tel +41 55 417 7603
Man Investments (CH) AG
Huobstrasse 3 | 8808
2009 Jun 01
1
write values of points beside points in plot
Hi everyone,
is it possible to write a certain value beside a point in a plot?
I'm plotting the following:
plot(coefficient$intercept ~ coefficient$average_BM_leaves_needles,
main="intercepts ::: BM_leaves_needles",
ylab="intercepts", xlab="average BM_leaves_needles per site [kg]")
and I want to have the value of coefficient$site_no written beside
each
2016 Apr 26
0
Linear Regressions with constraint coefficients
This is a quadratic programming problem that you can solve using
either a quadratic programming solver with constraints or a general
nonlinear solver with constraints. See
https://cran.r-project.org/web/views/Optimization.html
for more info on what is available.
Here is an example using a nonlinear least squares solver and
non-negative bound constraints. The constraint that the coefficients
sum
2011 Jul 18
1
question about linear mixed model
Hi all:
I have a question about linear mixed model.
my linear mixed model with randomized slope and intercept with interaction
of time and group(g1,g2,g3):
model<- glmmPQL(log10(CD4) ~ time + factor(group)+ time:factor(group),
random = ~time|id)
What I get is only the main and interaction of time and group.My question
is:
1. How can I get the g1,g2,g3's slope respectively?In other
2010 Apr 12
2
Interpreting factor*numeric interaction coefficients
Dear all,
I am a relative novice with R, so please forgive any terrible errors...
I am working with a GLM that describes a response variable as a function of
a categorical variable with three levels and a continuous variable. These
two predictor variables are believed to interact.
An example of such a model follows at the bottom of this message, but here
is a section of its summary table:
2009 Apr 03
2
Linear model, finding the slope
Hi
for some data I working on I am merely plotting time against temperature for
a variable named filmclip. So for example, I have volunteers who watched
various film clips and have used infared camera to monitor the temperature
on their face at every second of the clip.
The variable names I have used are Normalised ( for the temperature) and
Frame (for the time in seconds).
So I have fitted a
2010 Sep 06
1
Correct coefficients from treatment contrasts?
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2013 Apr 23
1
Writing contrast statements to test difference of slope in linear regressions
Hi Everyone,
I am uncertain that I am writing the contrast statements correctly. Basically, I'm unsure when to use a -1 and a 1 when writing the contrasts. Specifically I am interested in comparing the slopes between different temperature regimes. Temperature is therefore a factor. Time and percent are numerical. Using the gmodels package I made the following model:
2016 Apr 28
0
Linear Regressions with constraint coefficients
The nls2 package can be used to get starting values.
On Thu, Apr 28, 2016 at 8:42 AM, Aleksandrovic, Aljosa (Pfaeffikon)
<Aljosa.Aleksandrovic at man.com> wrote:
> Hi Gabor,
>
> Thanks a lot for your help!
>
> I tried to implement your nonlinear least squares solver on my data set. I was just wondering about the argument start. If I would like to force all my coefficients to
2007 Nov 28
2
fit linear regression with multiple predictor and constrained intercept
Hi group,
I have this type of data
x(predictor), y(response), factor (grouping x into many groups, with 6-20
obs/group)
I want to fit a linear regression with one common intercept. 'factor'
should only modify the slopes, not the intercept. The intercept is expected
to be >0.
If I use
y~ x + factor, I get a different intercept for each factor level, but one
slope only
if I use
y~ x *
2008 May 16
1
Making slope coefficients ``relative to 0''.
I am interested in whether the slopes in a linear model are different
from 0.
I.e. I would like to obtain the slope estimates, and their standard
errors,
``relative to 0'' for each group, rather than relative to some baseline.
Explicitly I would like to write/represent the model as
y = a_i + b_i*x + E
i = 1, ..., K, where x is a continuous variate and i indexes groups
(levels of a
2016 Apr 28
2
Linear Regressions with constraint coefficients
Hi Gabor,
Thanks a lot for your help!
I tried to implement your nonlinear least squares solver on my data set. I was just wondering about the argument start. If I would like to force all my coefficients to be inside an interval, let?s say, between 0 and 1, what kind of starting values are normally recommended for the start argument (e.g. Using a 4 factor model with b1, b2, b3 and b4, I tried
2007 Aug 14
4
Linear Regression with slope equals 0
Hi there, am trying to run a linear regression with a slope of 0.
I have a dataset as follows
t d
1 303
2 302
3 304
4 306
5 307
6 303
I would like to test the significance that these points would lie on a
horizontal straight line.
The standard regression lm(d~t) doesn't seem to allow the slope to be set.
Any help very welcome.
ed
2008 Dec 28
1
Random coefficients model with a covariate: coxme function
Dear R users:
I'm new to R and am trying to fit a mixed model
Cox regression model with coxme function.
I have one two-level factor (treat) and one
covariate (covar) and 32 different groups
(centers). I'd like to fit a random coefficients model, with treat and covar
as fixed factors and a random intercept, random
treat effect and random covar slope per center.
I haver a couple of