Displaying 20 results from an estimated 4000 matches similar to: "duration analysis"
2005 Jun 09
1
getting more than the coefficients
Hi there,
I am trying to export a regression output to Latex. I am using the xtable function in the xtable library. Doing
myfit <- lm(myformula, mydata)
print.xtable(xtable(myfit), file="myfile")
only returns the estimated coefficients and the correspondent standard erros, t-statiscs and p-values. But I wish to get a bit more, say, the number of observations used in the
2005 Oct 20
5
spliting an integer
Hi there,
From the vector X of integers,
X = c(11999, 122000, 81997)
I would like to make these two vectors:
Z= c(1999, 2000, 1997)
Y =c(1 , 12 , 8)
That is, each entry of vector Z receives the four last digits of each entry of X, and Y receives "the rest".
Any suggestions?
Thanks in advance,
Dimitri
[[alternative HTML version deleted]]
2006 Jan 26
1
efficiency with "%*%"
Hi,
x and y are (numeric) vectors. I wonder if one of the following is more
efficient than the other:
x%*%y
or
sum(x*y)
?
Thanks,
Dimitri Szerman
2008 Apr 18
1
Overall p-value from a factor in a coxph fit
Hi all.
If I run the simple regression when x is a categorical variable ( x <-
factor(x) ):
> MyFit <-coxph( Surv(start, stop, event) ~ x )
How can I get the overall p-value on x other than for each dummy
variable?
> anova(MyFit)
does NOT provide that information as previously suggested on the list.
All the best,
Kare
[[alternative HTML version deleted]]
2005 Oct 25
2
Inf in regressions
Hi,
Suppose I I wish to run
lm( y ~ x + z + log(w) )
where w assumes non-negative values. A problem arises when w=0, as log(0)
= -Inf, and R doesn't accept that (as it "accepts" NA). Is there a way to
tell R to do with -Inf the same it does with NA, i.e, to ignore it? (
Otherwise I have to do something like
w[w==0] <- NA
which doesn't hurt, but might be a bit
2005 Jun 24
2
Gini with frequencies
Hi there,
I am trying to compute Gini coefficients for vectors containing income classes. The data I possess look loke this:
yit <- c(135, 164, 234, 369)
piit <- c(367, 884, 341, 74 )
where yit is the vector of income classes, and fit is the vector of associated frequencies.(This data is from Rustichini, Ichino and Checci (Journal of Public Economics, 1999) ). In ineq pacakge, Gini( )
2017 Jun 18
0
R_using non linear regression with constraints
> On Jun 18, 2017, at 6:24 AM, Manoranjan Muthusamy <ranjanmano167 at gmail.com> wrote:
>
> I am using nlsLM {minpack.lm} to find the values of parameters a and b of
> function myfun which give the best fit for the data set, mydata.
>
> mydata=data.frame(x=c(0,5,9,13,17,20),y = c(0,11,20,29,38,45))
>
> myfun=function(a,b,r,t){
> prd=a*b*(1-exp(-b*r*t))
>
2017 Jun 18
0
R_using non linear regression with constraints
I ran the following script. I satisfied the constraint by
making a*b a single parameter, which isn't always possible.
I also ran nlxb() from nlsr package, and this gives singular
values of the Jacobian. In the unconstrained case, the svs are
pretty awful, and I wouldn't trust the results as a model, though
the minimum is probably OK. The constrained result has a much
larger sum of squares.
2017 Jun 18
3
R_using non linear regression with constraints
https://cran.r-project.org/web/views/Optimization.html
(Cran's optimization task view -- as always, you should search before posting)
In general, nonlinear optimization with nonlinear constraints is hard,
and the strategy used here (multiplying by a*b < 1000) may not work --
it introduces a discontinuity into the objective function, so
gradient based methods may in particular be
2020 Oct 17
2
??? is to nls() as abline() is to lm() ?
I'm drawing a fitted normal distribution over a histogram. The use case is trivial (fitting normal distributions on densities) but I want to extend it to other fitting scenarios. What has stumped me so far is how to take the list that is returned by nls() and use it for curve(). I realize that I can easily do all of this with a few intermediate steps for any specific case. But I had expected
2006 Apr 29
1
splitting and saving a large dataframe
Hi,
I searched for this in the mailing list, but found no results.
I have a large dataframe ( dim(mydata)= 1297059 16, object.size(mydata=
145280576) ) , and I want to perform some calculations which can be done by
a factor's levels, say, mydata$myfactor. So what I want is to split this
dataframe into nlevels(mydata$myfactor) = 80 levels. But I must do this
efficiently, that is, I
2006 Jul 05
1
creating a data frame from a list
Dear all,
I have a list with three (named) numeric vectors:
> lst = list(a=c(A=1,B=8) , b=c(A=2,B=3,C=0), c=c(B=2,D=0) )
> lst
$a
A B
1 8
$b
A B C
2 3 0
$c
B D
2 0
Now, I'd love to use this list to create the following data frame:
> dtf = data.frame(a=c(A=1,B=8,C=NA,D=NA),
+ b=c(A=2,B=3,C=0,D=NA),
+ c=c(A=NA,B=2,C=NA,D=0) )
> dtf
a b
2006 Jul 12
1
help in vectorization
Hi,
I have two data frames. One is like
> dtf = data.frame(y=c(rep(2002,4), rep(2003,5)),
+ m=c(9:12, 1:5),
+ def=c(.74,.75,.76,.78,.80,.82,.85,.85,.87))
and the other
dtf2 = data.frame(y=rep( c(2002,2003),20),
m=c(trunc(runif(20,1,5)),trunc(runif(20,9,12))),
inc=rnorm(40,mean=300,sd=150) )
What I want is to divide
2017 Jun 18
0
R_using non linear regression with constraints
I've seen a number of problems like this over the years. The fact that the singular values of the Jacobian have
a ration larger than the usual convergence tolerances can mean the codes stop well before the best fit. That is
the "numerical analyst" view. David and Jeff have given geometric and statistical arguments. All views are useful,
but it takes some time to sort them all out and
2020 Oct 17
0
??? is to nls() as abline() is to lm() ?
I haven't followed your example closely, but can't you use the predict()
method for this? To draw a curve, the function that will be used in
curve() sets up a newdata dataframe and passes it to predict(fit,
newdata= ...) to get predictions at those locations.
Duncan Murdoch
On 17/10/2020 5:27 a.m., Boris Steipe wrote:
> I'm drawing a fitted normal distribution over a
2017 Jun 18
3
R_using non linear regression with constraints
I am not as expert as John, but I thought it worth pointing out that the
variable substitution technique gives up one set of constraints for
another (b=0 in this case). I also find that plots help me see what is
going on, so here is my reproducible example (note inclusion of library
calls for completeness). Note that NONE of the optimizers mentioned so far
appear to be finding the true best
2012 Aug 25
2
Standard deviation from MANOVA??
Hi,
I have problem getting the standard deviation from the manova output.
I have used the manova function: myfit <- manova(cbind(y1, y2) ~ x1
+ x2 + x3, data=mydata) .
I tried to get the predicted values and their standard deviation by using:
predict(myfit, type="response", se.fit=TRUE)
But the problem is that I don't get the standard deviation values, I only
2008 Feb 24
1
what missed ----- CART
Hi all,
Can anyone who is familar with CART tell me what I missed in my tree code?
library (MASS)
myfit <- tree (y ~ x1 + x2 + x3 + x4 )
# tree.screens () # useless
plot(myfit); text (myfit, all= TRUE, cex=0.5, pretty=0)
# tile.tree (myfit, fgl$type) # useless
# close.screen (all= TRUE) # useless
My current tree plot resulted from above code shows as:
2011 Jan 25
1
Predictions with 'missing' variables
Dear List,
I think I'm going crazy here...can anyone explain why do I get the same
predictions in train and test data sets below when the second has a missing
input?
y <- rnorm(1000)
x1 <- rnorm(1000)
x2 <- rnorm(1000)
train <- data.frame(y,x1,x2)
test <- data.frame(x1)
myfit <- glm(y ~ x1 + x2, data=train)
summary(myfit)
all(predict(myfit, test) == predict(myfit, train))
2003 Oct 23
3
List of lm objects
Hi R-Helpers:
I?m trying to fit the same linear model to a bunch of variables in a data
frame, so I was trying to adapt the codes John Fox, Spencer Graves and Peter
Dalgaard proposed and discused yesterday on this e-mail list:
for (y in df[, 3:5]) {
mod = lm(y ~ Trt*Dose, data = x, contrasts = list(Trt =
contr.sum, Dose = contr.sum))
Anova(mod, type = "III")
} ## by John Fox
or
for