Displaying 20 results from an estimated 8000 matches similar to: "model selection using ANOVA"
2008 Nov 17
2
looking for matches
My question is probably pretty basic, but since I'm really new to R, here it
goes ....
I have two separate data frames that include class names and various other
information on classes. I'm trying to create a match based on class names
and if a match exists to create a third data frame with the class name.
I was hoping to accomplish this with sapply, but I can't figure out if I can
2011 Jun 20
3
importing a file
I haven't used R in a couple of years, and now am trying something as
simple as importing a csv file and am running into problems right away.
*
mydata <- read.csv (Wordata1.csv, sep="")
Error in read.table(file = file, header = header, sep = sep, quote = quote,
:
object 'Wordata1.csv' not found
*I've tried in both as as read.csv and read.table and still get the
2009 Jan 21
2
Replacing dates with consecutive observations
I am working with a list of dates and I would like to replace each date with
the one that comes after, ie. 1/1/07 will become 1/5/07, 1/5/07 will become
1/7/07, etc. The number of days between my dates always varies, so I can't
just increase each one by 5 days or so. Does anyone know of a way I can do
this in R?
thank you
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2011 Jun 21
5
converting character to numeric
I'm trying to convert data from character to numeric.
I've imported data as a csv file, I'm assuming that the import is a
database - are all the columns in a database considered "vectors" and that
they can be operated on individually
Therefore I've tried the following
mydata <- as.numeric(mydata$apples)
when i then look at mydata again the named column is still
2009 Feb 19
2
colored maps again
I'm trying to create a colored map that would show the number of students
per state.
My data frame consists of two columns - state and count.
I'm using the following code
library(maps)
map("usa")
library(plotrix)
state.col<-color.scale(gre$count,0,0,c(0,1))
map("state",fill=TRUE,col=state.col)
I'm getting a map, but the values are not being mapped to correct
2010 Jul 05
2
Can anybody help me understand AIC and BIC and devise a new metric?
Hi all,
Could anybody please help me understand AIC and BIC and especially why do
they make sense?
Furthermore, I am trying to devise a new metric related to the model
selection in the financial asset management industry.
As you know the industry uses Sharpe Ratio as the main performance
benchmark, which is the annualized mean of returns divided by the annualized
standard deviation of returns.
2009 Mar 31
1
target of assignment expands to non-language object
I'm running the following code
numbers <- 1:50
for (i in 1:50)
assign(paste("model",numbers[i]),i)<-(lm(temp$Overall.Scaled.Score~temp$raw.score))
where I want R to create 50 different models-1:50, but get the following
error message
"target of assignment expands to non-language object". I've tried it with
2009 Feb 17
2
creating a map
I'm trying to create a fairly basic map using R. What i want to get is the
map of the country with circles representing a count of students in each
state.
What I've done so far is as following -
map("state")
symbols(data1$count,circles=log(data1$count)*3,fg=col,bg=col,add=T,inches=F)
this gives me the map of the country, but one that's not populated by my
counts.
Does
2009 Mar 04
1
mapping lat and long with maps package
I am trying to overlay a data frame with lat and longitude(which refer to
zip codes) on the map of US that I get by using map ("states").
Is there anyway to do this or do I have to resort to using maptools?
thank you
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2008 Jun 21
1
stepAIC {MASS}
In a generalized linear model with k covariates, there are 2(kth power) - 1
possible models (excluding interactions).
Awhile ago a posting to R-help suggested Model Selection and Multimodel
Inference, 2nd ed, by Burnham and Anderson as a good source for
understanding model selection. They recommend (page 71) computing AIC
differences over all candidate models in the set of possible models.
After
2006 Jan 30
4
Logistic regression model selection with overdispersed/autocorrelated data
I am creating habitat selection models for caribou and other species with
data collected from GPS collars. In my current situation the radio-collars
recorded the locations of 30 caribou every 6 hours. I am then comparing
resources used at caribou locations to random locations using logistic
regression (standard habitat analysis).
The data is therefore highly autocorrelated and this causes Type
2010 Jun 29
1
Model validation and penalization with rms package
I?ve been using Frank Harrell?s rms package to do bootstrap model
validation. Is it the case that the optimum penalization may still
give a model which is substantially overfitted?
I calculated corrected R^2, optimism in R^2, and corrected slope for
various penalties for a simple example:
x1 <- rnorm(45)
x2 <- rnorm(45)
x3 <- rnorm(45)
y <- x1 + 2*x2 + rnorm(45,0,3)
ols0 <- ols(y
2004 Jun 01
1
multi-model inference
Hello
I've been investigating using multi-model inference, based on calculating
AIC and AIC weights, using the techniques outlined in Burnham and
Anderson's (2002) book. However I notice a couple of emails in the R-help
archive stating that there are errors in the technique. Are these errors
associated with the particular implementation that B & A propose in their
text, or is the
2006 Feb 20
1
Nested AIC
Greetings,
I have recently come into some confusion over weather or not AIC
results for comparing among models requires that they be nested.
Reading Burnham & Anderson (2002) they are explicit that nested
models are not required, but other respected statisticians have
suggested that nesting is a pre-requisite for comparison. Could
anyone who feels strongly regarding either position
2007 Dec 09
2
Large determinant problem
I thought I would have another try at explaining my problem. I think that
last time I may have buried it in irrelevant detail.
This output should explain my dilemma:
> dim(S)
[1] 1455 269
> summary(as.vector(S))
Min. 1st Qu. Median Mean 3rd Qu. Max.
-1.160e+04 0.000e+00 0.000e+00 -4.132e-08 0.000e+00 8.636e+03
> sum(as.vector(S)==0)/(1455*269)
[1]
2009 Apr 15
2
AICs from lmer different with summary and anova
Dear R Helpers,
I have noticed that when I use lmer to analyse data, the summary function
gives different values for the AIC, BIC and log-likelihood compared with the
anova function.
Here is a sample program
#make some data
set.seed(1);
datx=data.frame(array(runif(720),c(240,3),dimnames=list(NULL,c('x1','x2','y'
))))
id=rep(1:120,2); datx=cbind(id,datx)
#give x1 a
2009 Oct 22
4
Bayesian regression stepwise function?
Hi everyone,
I am wondering if there exists a stepwise regression function for the
Bayesian regression model. I tried googling, but I couldn't find anything.
I know "step" function exists for regular stepwise regression, but nothing
for Bayes.
Thanks
--
View this message in context: http://www.nabble.com/Bayesian-regression-stepwise-function--tp26013725p26013725.html
Sent from
2007 Mar 09
4
Reg. strings and numeric data in matrix.
Hi All,
Sorry for this basic question as I am new to this R. I would like to know,
is it possible to consider a matrix with some columns having numeric data
and some other's with characters (strings) data? How do I get this type of
data from a flat file.
Thanks very much,
mallika
____________________________________________________________________________
Mallika Veeramalai, Ph.D.,
2004 Dec 22
2
GAM: Overfitting
I am analyzing particulate matter data (PM10) on a small data set (147
observations). I fitted a semi-parametric model and am worried about
overfitting. How can one check for model fit in GAM?
Jean G. Orelien
2003 Jul 04
1
Quasi AIC
Dear all,
Using the quasibinomial and quasipoisson families results in no AIC being
calculated. However, a quasi AIC has actually been defined by Lebreton et al
(1992). In the (in my opinon, at least) very interesting book by Burnham and
Anderson (1998,2002) this QAIC (and also QAICc) is covered. Maybe this is something
that could be implemented in R.
Take a look at page 23 in this pdf: