Displaying 20 results from an estimated 100 matches similar to: "Marginality rule between powers and interaction terms in lm()"
2011 Jan 22
0
how to call BayesX in R to see the graph
Hi Everybody,
please can you help me how to call BayesX in R in order to see the graph
already exist in BayesX
Thanks
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Date: Sat, Jan 22, 2011 at 5:00 AM
Subject: R-help Digest, Vol 95, Issue 22
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2008 Apr 28
0
Take marginality into account in factor.scope
Dear devellopeRs,
I've altered factor.scope() from the stats package so it can take
marginality into account. Therefore I've added the argument marginal.
When marginal is NULL, factor.scope() works like the original version.
The marginality is to be specified as a named list. The name of the
elements is the name of a variable. The content of the element is a
character vector with the
2008 May 25
1
marginality principle / selecting the right type of SS for an interaction hypothesis
Hello,
I have a problem with selecting the right type of sums of squares for
an ANCOVA for my specific experimental data and hypotheses. I do have
a basic understanding of the differences between Type-I, II, and III
SSs, have read about the principle of marginality, and read Venable's
"Exegeses on Linear Models" 
(http://www.stats.ox.ac.uk/pub/MASS3/Exegeses.pdf). I am pretty new to
2017 Oct 31
0
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hi Arie,
Thank you for your further research into the issue.
Regarding Stata: On the other hand, JMP gives model matrices that use the
main effects contrasts in computing the higher order interactions, without
the dummy variable encoding. I verified this both by analyzing the linear
model given in my first example and noting that JMP has one more degree of
freedom than R for the same model, as
2017 Nov 02
0
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hi Arie,
The book out of which this behavior is based does not use factor (in this
section) to refer to categorical factor. I will again point to this
sentence, from page 40, in the same section and referring to the behavior
under question, that shows F_j is not limited to categorical factors:
"Numeric variables appear in the computations as themselves, uncoded.
Therefore, the rule does not
2017 Nov 04
0
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hi Arie,
I understand what you're saying. The following excerpt out of the book
shows that F_j does not refer exclusively to categorical factors: "...the
rule does not do anything special for them, and it remains valid, in a
trivial sense, whenever any of the F_j is numeric rather than categorical."
Since F_j refers to both categorical and numeric variables, the behavior of
2017 Nov 06
0
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hi Arie,
Given the heuristic, in all of my examples with a missing two-factor
interaction the three-factor interaction should be coded with dummy
variables. In reality, it is encoded by dummy variables only when the
numeric:numeric interaction is missing, and by contrasts for the other two.
The heuristic does not specify separate behavior for numeric vs categorical
factors (When the author of
2017 Nov 02
2
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hello Tyler,
Thank you for searching for, and finding, the basic description of the
behavior of R in this matter.
I think your example is in agreement with the book.
But let me first note the following. You write: "F_j refers to a
factor (variable) in a model and not a categorical factor". However:
"a factor is a vector object used to specify a discrete
classification"
2017 Oct 27
2
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hello Tyler,
I want to bring to your attention the following document: "What
happens if you omit the main effect in a regression model with an
interaction?" (https://stats.idre.ucla.edu/stata/faq/what-happens-if-you-omit-the-main-effect-in-a-regression-model-with-an-interaction).
This gives a useful review of the problem. Your example is Case 2: a
continuous and a categorical regressor.
2017 Nov 04
2
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hello Tyler,
I rephrase my previous mail, as follows:
In your example, T_i = X1:X2:X3. Let F_j = X3. (The numerical
variables X1 and X2 are not encoded at all.) Then T_{i(j)} = X1:X2,
which in the example is dropped from the model. Hence the X3 in T_i
must be encoded by dummy variables, as indeed it is.
  Arie
On Thu, Nov 2, 2017 at 4:11 PM, Tyler <tylermw at gmail.com> wrote:
> Hi
2017 Jun 29
0
Help : glm p-values for a factor predictor
Hi Michael,
> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Michael
> Friendly
> Sent: Thursday, June 29, 2017 9:04 AM
> To: Beno?t PELE <benoit.pele at acoss.fr>; r-help at r-project.org
> Subject: Re: [R] Help : glm p-values for a factor predictor
> 
> On 6/29/17 11:13 AM, Beno?t PELE wrote:
> > My question is
2003 Apr 26
0
new package: effects
I've uploaded to CRAN a new package called effects. The package contains 
functions for tabular or graphical display of terms in a linear or 
generalized linear model, and is particularly suitable for models that 
contain terms -- such as main effects and interactions, or polynomial 
regressors -- related by marginality (hierarchy). A draft paper describing 
the package is located at 
2003 Apr 26
0
new package: effects
I've uploaded to CRAN a new package called effects. The package contains 
functions for tabular or graphical display of terms in a linear or 
generalized linear model, and is particularly suitable for models that 
contain terms -- such as main effects and interactions, or polynomial 
regressors -- related by marginality (hierarchy). A draft paper describing 
the package is located at 
2012 Nov 08
1
Package "glmulti": Include a variable in ALL models
Dear all,
I have a question about the glmulti package. I want to include some variables in all models. To that end I applied the wrapper function as shown in the examples (http://www.inside-r.org/packages/cran/glmulti/docs/glmulti).
To include the variable "Geslacht" in all models:
> glm.redefined = function(formula, data, always="", ...)
2017 Nov 06
2
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hello Tyler,
You write that you understand what I am saying. However, I am now at
loss about what exactly is the problem with the behavior of R.  Here
is a script which reproduces your experiments with three variables
(excluding the full model):
m=expand.grid(X1=c(1,-1),X2=c(1,-1),X3=c("A","B","C"))
model.matrix(~(X1+X2+X3)^3-X1:X3,data=m)
2017 Nov 29
0
How to extract coefficients from sequential (type 1), ANOVAs using lmer and lme
(This time with the r-help in the recipients...)
Be careful when mixing lme4 and lmerTest together -- lmerTest extends
and changes the behavior of various lme4 functions.
>From the help page for lme4-anova (?lme4::anova.merMod)
>      ?anova?: returns the sequential decomposition of the contributions
>           of fixed-effects terms or, for multiple arguments, model
>          
2012 Jun 12
1
Two-way linear model with interaction but without one main effect
Hi,
I know that the type of model described in the subject line violates
the principle of marginality and it is rare in practice, but there may
be some circumstances where it has sense. Let's take this imaginary
example (not homework, just a silly made-up case for illustrating the
rare situation):
I'm measuring the energy absorption of sports footwear in jumping. I
have three models (S1,
2006 Oct 31
0
6375225 PM_IDLE_DOWN is not enforced after console framebuffer powers off
Author: osaeed
Repository: /hg/zfs-crypto/gate
Revision: 3881b24561f17fe3d8926e85bbbefa1de3c86c43
Log message:
6375225 PM_IDLE_DOWN is not enforced after console framebuffer powers off
Files:
	update: usr/src/uts/common/os/sunpm.c
2013 Feb 08
2
Coercing of types when raising a number to a series of powers
I'm trying to produce a series of powers of a number as follows:
  |> 0.05^0:5
   [1] 1 2 3 4 5
This is not the result I expected. I guess some kind of coercion happened,
since,
  |> class(0.05^0:5)
   [1] "integer"
Could anyone explain me what is happening here?
Thanks,
  -Sergio.
2005 Oct 31
3
question about precision, floor, and powers of two.
At the risk of being beaten about the face and body, can somebody explain
why the middle example: log2(2^3); floor(log2(2^3)) is different than
examples 1 and 3?
> log2(2^2); floor(log2(2^2))
[1] 2
[1] 2
> log2(2^3); floor(log2(2^3))
[1] 3
[1] 2
> log2(2^4); floor(log2(2^4))
[1] 4
[1] 4
>
DrC
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