Displaying 20 results from an estimated 2000 matches similar to: "The math underlying the `betareg' package?"
2006 Apr 17
1
using betareg: problems with anova and predict
Dear R-helpers:
We have had fun using betareg to fit models with proportions as
dependent variables.
However, in the analysis of these models we found some wrinkles and
don't know where is the best place to start looking for a fix.
The problems we see (so far) are that
1. predict ignores newdata
2. anova does not work
Here is the small working example:
----------------------------
x
2011 Sep 01
3
betareg question - keeping the mean fixed?
Hello,
I have a dataset with proportions that vary around a fixed mean, is it
possible to use betareg to look at variance in the dispersion parameter
while keeping the mean fixed?
I am very new to R but have tried the following:
svec<-c(qlogis(mean(data1$scaled)),0,0,0)
f<-betareg(scaled~-1 | expt_label + grouped_hpi, data=data1, link.phi="log",
2006 Mar 06
3
Interleaving elements of two vectors?
Suppose one has
x <- c(1, 2, 7, 9, 14)
y <- c(71, 72, 77)
How would one write an R function which alternates between elements of
one vector and the next? In other words, one wants
z <- c(x[1], y[1], x[2], y[2], x[3], y[3], x[4], y[4], x[5], y[5])
I couldn't think of a clever and general way to write this. I am aware
of gdata::interleave() but it deals
2009 Feb 13
1
need help with errors in betareg analysis
Hi
I'm trying to fit a model in betareg and I'm getting errors, but have no
idea what they mean or how to solve them. Does anyone have experience with
this?
> model <- betareg(ACT ~ ST*SoilT, data = actDL_F)
Warning messages:
1: In sqrt(W) : NaNs produced
2: In sqrt(W) : NaNs produced
3: In sqrt(1 + phihat) : NaNs produced
data summaries don't give any na's or problems I
2011 Jun 24
3
Error using betareg
Dear all,
I get an error using betrag on this data set
:http://dl.dropbox.com/u/1866110/dump.csv.
I run it like this
regression f2.1=betareg(Y~X1+X2,data=dump)
summary(f2.1)
I get :
Call:
betareg(formula = Y ~ X1 + X2, data = dump)
Standardized weighted residuals 2:
Error in quantile.default(x$residuals) :
missing values and NaN's not allowed if 'na.rm' is FALSE
In addition:
2006 Jan 26
2
Prediction when using orthogonal polynomials in regression
Folks,
I'm doing fine with using orthogonal polynomials in a regression context:
# We will deal with noisy data from the d.g.p. y = sin(x) + e
x <- seq(0, 3.141592654, length.out=20)
y <- sin(x) + 0.1*rnorm(10)
d <- lm(y ~ poly(x, 4))
plot(x, y, type="l"); lines(x, d$fitted.values, col="blue") # Fits great!
all.equal(as.numeric(d$coefficients[1] + m
2005 Jun 07
1
R and MLE
I learned R & MLE in the last few days. It is great! I wrote up my
explorations as
http://www.mayin.org/ajayshah/KB/R/mle/mle.html
I will be most happy if R gurus will look at this and comment on how
it can be improved.
I have a few specific questions:
* Should one use optim() or should one use stats4::mle()?
I felt that mle() wasn't adding much value compared with optim, and
2011 Mar 12
3
betareg help
Dear R users,
I'm trying to do betareg on my dataset.
Dependent variable is not normally distributed and is proportion (of condom
use (0,1)).
But I'm having problems:
gyl<-betareg(cond ~ alcoh + drug, data=results)
Error in optim(par = start, fn = loglikfun, gr = gradfun, method = method, :
initial value in 'vmmin' is not finite
Why is R returning me error in optim()?
What
2005 May 27
1
R commandline editor question
I am using R 2.1 on Apple OS X.
When I get the ">" prompt, I find it works well with emacs commandline
editing. Keys like M-f C-k etc. work fine.
The one thing that I really yearn for, which is missing, is bracket
matching When I am doing something which ends in )))) it is really
useful to have emacs or vi-style bracket matching, so as to be able
to visually keep track of whether I
2005 May 08
2
Need a factor level even though there are no observations
I'm in this situation:
factorlabels <- c("School", "College", "Beyond")
with data for 8 families:
education.man <- c(1,2,1,2,1,2,1,2) # Note : no "3" values
education.wife <- c(1,2,3,1,2,3,1,2) # 1,2,3 are all present.
My goal is to create this table:
School College Beyond
2005 Aug 19
1
Problem with get.hist.quote() in tseries
When using get.hist.quote(), I find the dates are broken. This is with
R 2.1.1 on Mac OS X `panther'.
> library(tseries)
Loading required package: quadprog
'tseries' version: 0.9-27
'tseries' is a package for time series analysis and computational
finance.
See 'library(help="tseries")' for details.
> x <-
2005 Jul 12
2
Puzzled at ifelse()
I have a situation where this is fine:
> if (length(x)>15) {
clever <- rr.ATM(x, maxtrim=7)
} else {
clever <- rr.ATM(x)
}
> clever
$ATM
[1] 1848.929
$sigma
[1] 1.613415
$trim
[1] 0
$lo
[1] 1845.714
$hi
[1] 1852.143
But this variant, using ifelse(), breaks:
> clever <- ifelse(length(x)>15, rr.ATM(x, maxtrim=7), rr.ATM(x))
2005 May 24
1
Catching an error with lm()
Folks,
I'm in a situation where I do a few thousand regressions, and some of
them are bad data. How do I get back an error value (return code such
as NULL) from lm(), instead of an error _message_?
Here's an example:
> x <- c(NA, 3, 4)
> y <- c(2, NA, NA)
> d <- lm(y ~ x)
Error in lm.fit(x, y, offset = offset, singular.ok = singular.ok, ...) :
0 (non-NA) cases
2005 Jun 14
1
Puzzled in utilising summary.lm() to obtain Var(x)
I have a program which is doing a few thousand runs of lm(). Suppose
it is a simple model
y = a + bx1 + cx2 + e
I have the R object "d" where
d <- summary(lm(y ~ x1 + x2))
I would like to obtain Var(x2) out of "d". How might I do it?
I can, of course, always do sd(x2). But it would be much more
convenient if I could snoop around the contents of summary.lm and
2005 Aug 16
1
Extracting some rows from a data frame - lapses into a vector
I have a data frame with one column "x":
> str(data)
`data.frame': 20 obs. of 1 variable:
$ x: num 0.0495 0.0986 0.9662 0.7501 0.8621 ...
Normally, I know that the notation dataframe[indexes,] gives you a new
data frame which is the specified set of rows. But I find:
> str(data[1:10,])
num [1:10] 0.0495 0.0986 0.9662 0.7501 0.8621 ...
Here, it looks like the operation
2005 Sep 25
1
Question on lm(): When does R-squared come out as NA?
I have a situation with a large dataset (3000+ observations), where
I'm doing lags as regressors, where I get:
Call:
lm(formula = rj ~ rM + rM.1 + rM.2 + rM.3 + rM.4)
Residuals:
1990-06-04 1994-11-14 1998-08-21 2002-03-13 2005-09-15
-5.64672 -0.59596 -0.04143 0.55412 8.18229
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -0.003297 0.017603
2006 Aug 14
1
Presentation of multiple models in one table using xtable
Consider this situation:
> x1 <- runif(100); x2 <- runif(100); y <- 2 + 3*x1 - 4*x2 + rnorm(100)
> m1 <- summary(lm(y ~ x1))
> m2 <- summary(lm(y ~ x2))
> m3 <- summary(lm(y ~ x1 + x2))
Now you have estimated 3 different "competing" models, and suppose you
want to present the set of models in one table. xtable(m1) is cool,
but doing that thrice would give
2005 Oct 01
1
Placing axes label strings closer to the graph?
Folks,
I have placed an example of a self-contained R program later in this
mail. It generates a file inflation.pdf. When I stare at the picture,
I see the "X label string" and "Y label string" sitting lonely and far
away from the axes. How can these distances be adjusted? I read ?par
and didn't find this directly.
I want to hang on to 2.8 x 2.8 inches as the overall size
2005 Aug 04
1
Puzzled at rpart prediction
I'm in a situation where I say:
> predict(m.rpart, newdata=D[N1+t,])
0 1
173 0.8 0.2
which I interpret as meaning: an 80% chance of "0" and a 20% chance of
"1". Okay. This is consistent with:
> predict(m.rpart, newdata=D[N1+t,], type="class")
[1] 0
Levels: 0 1
But I'm puzzled at the following. If I say:
> predict(m.rpart,
2005 Oct 08
1
Rpart -- using predict() when missing data is present?
I am doing
> library(rpart)
> m <- rpart("y ~ x", D[insample,])
> D[outsample,]
y x
8 0.78391922 0.579025591
9 0.06629211 NA
10 NA 0.001593063
> p <- predict(m, newdata=D[9,])
Error in model.frame(formula, rownames, variables, varnames, extras, extranames, :
invalid result from na.action
How do I persuade him to give me NA