Displaying 20 results from an estimated 500 matches similar to: "competing risks survival analysis"
2011 Oct 31
1
Question on estimating standard errors with noisy signals using the quantreg package
Dear all,
My question might be more of a statistics question than a question on R,
although it's on how to apply the 'quantreg' package. Please accept my
apologies if you believe I am strongly misusing this list.
To be very brief, the problem is that I have data on only a random draw, not
all of doctors' patients. I am interested in the, say, median number of
patients of
2010 Mar 03
1
empirical copula code
Hi all,
I have this data set:
## Empirical copula
## dt1 = ranking
## dt2 = observed uniform data associated with the ranking
Sample data,
> dt1
S_i R_i
[1,] 7.0 10.0
[2,] 232.5 440.5
[3,] 143.0 141.5
[4,] 272.5 222.0
[5,] 46.0 34.0
[6,] 527.0 483.0
[7,] 420.5 563.5
[8,] 23.5 16.5
[9,] 56.5 68.5
[10,] 341.5 382.5
> dt2
unisk1 unisk2
[1,] 0.008 0.010
2005 Sep 13
4
plot(<lm>): new behavior in R-2.2.0 alpha
As some of you R-devel readers may know, the plot() method for
"lm" objects is based in large parts on contributions by John
Maindonald, subsequently "massaged" by me and other R-core
members.
In the statistics litterature on applied regression, people have
had diverse oppinions on what (and how many!) plots should be
used for goodness-of-fit / residual diagnostics, and to my
2009 Jul 07
1
error: no such index at level 2
Hi,
I am confused about how to select elements from a list.
I'm trying to select all rows of a table 'crossRsorted' such that the
mean of a related vector is > 0. The related vector is accessible as
a list element l[[i]] where i is the row index.
I thought this would work:
> crossRsorted[mean(q[[ crossRsorted[,1] ]], na.rm = TRUE) > 0, ]
Error in q[[crossRsorted[, 1]]] :
2005 Feb 11
1
cook's distance in weighted regression
I have a puzzle as to how R is computing Cook's distance in weighted linear
regression.
In
this case cook's distance should be given not as in OLS case by
h_ii*r_i^2/(1-hii)^2 divided by k*s^2 (1)
(where r is plain unadjusted residual, k is number of parameters in model,
etc. )
but rather by
w_ii*h_ii*r_i^2/(1-hii)^2 divided by k*s^2,
2010 Apr 20
1
3D surface plot with wireframe or persp?
Hello Dear,
I have a function, like z=f(x,y), and try a surface plot with this function.
But, on the reference of "wireframe" requires data option, so I generated x
and y, and computed z with them. But, still I have a problem to draw a
surface plot. The code and errors are
##################################################
mle_beta0=64.43707;
mle_beta1=-24365.16;
# generating for
2002 Dec 10
3
clogit and general conditional logistic regression
Can someone clarify what I cannot make out from the
documentation?
The function 'clogit' in the 'survival' package is
described as performing a "conditional logistic regression".
Its return value is stated to be "an object of class clogit
which is a wrapper for a coxph object."
This suggests that its usefulness is confined to the sort of
data which arise in
2004 Apr 18
2
lm with data=(means,sds,ns)
Hi Folks,
I am dealing with data which have been presented as
at each x_i, mean m_i of the y-values at x_i,
sd s_i of the y-values at x_i
number n_i of the y-values at x_i
and I want to linearly regress y on x.
There does not seem to be an option to 'lm' which can
deal with such data directly, though the regression
problem could be algebraically
2002 Apr 09
3
expressions on graphs
Hello,
I am trying to get a time derivative on a plot title. I prefer to have
it in the form \dot{s_i}, but \partial s_i/\partial t would be O.K. In
the graphics demo I cannot find either a dot or a partial equivalent.
Thanks,
John.
--
==========================================
John Janmaat
Department of Economics
Acadia University, Wolfville, NS, B0P 1X0
(902)585-1461
All opinions stated
2017 Aug 28
5
"Improvement with the R code"
Hello,
I am trying to implement a formula
aij= transition from state S_i to S_j/no of transition at state S_i
Code I have written is working with three state {1,2,3 }, but if the number
of states become={1,2,3,4,......n} then the code will not work, so can some
help me with this.
For and some rows of my data frame look like
2012 Jan 18
1
Non-linear Least Square Optimization -- Function of two variables.
Dear All,
In the past I have often used minpack (http://bit.ly/zXVls3) relying
on the Levenberg-Marquardt algorithm to perform non-linear fittings.
However, I have always dealt with a function of a single variable.
Is there any difference if the function depends on two variables?
To fix the ideas, please consider the function
f(R,N)=(a/(log(2*N))+b)*R+c*N^d,
where a,b,c,d are fit parameters.
For
2004 Apr 09
1
loess' robustness weights in loess
hi!
i want to change the "robustness weights" used by loess. these
are described on page 316 of chambers and hastie's "statistical models in S"
book as
r_i = B(e_i,6m)
where B is tukey's biweight function, e_i are the residulas, and m is the
median average distance from 0 of the residuals. i want to
change 6m to, say, 3m.
is there a way to do this? i cant
2011 Sep 02
1
Hints for Data Clustering
Dear All,
I will be confronted (relatively soon) with the following problem:
given a set of known statistical indicators {s_i} , i=1,2...N for a N
countries I would like to be able to do some data clustering i.e.
determining the best way to partition the N countries according to their
known properties, encoded by the {s_i} set of indicators for those
countries.
Some properties of these
2007 Feb 17
1
Constraint maximum (likelihood) using nlm
Hi,
I'm trying to find the maximum (likelihood) of a function. Therefore,
I'm trying to minimize the negative likelihood function:
# params: vector containing values of mu and sigma
# params[1] - mu, params[2]- sigma
# dat: matrix of data pairs y_i and s_i
# dat[,1] - column of y_i , dat[,2] column of s_i
negll <- function(params,dat,constant=0)
{
for(i in 1:length(dat[,1]))
{
2011 Sep 14
1
Hints for Data Mining
Dear All,
I am recycling a previous email of mine where I asked some questions
about clustering mixed numerical/categorical data. This time I am more
into data mining. I am given a set of known statistical indexes {s_i},
i=1,2...N for a N countries. These indexes in general are a both
numerical and categorical variables. For each country, I also have a
property x_i whose value is known, but
2005 Jun 10
1
Estimate of baseline hazard in survival
Dear All,
I'm having just a little terminology problem, relating the language used in
the Hosmer and Lemeshow text on Applied Survival Analysis to that of the
help that comes with the survival package.
I am trying to back out the values for the baseline hazard, h_o(t_i), for
each event time or observation time.
Now survfit(fit)$surv gives me the value of the survival function,
S(t_i|X_i,B),
2017 Aug 28
0
"Improvement with the R code"
Hi,
I think you overthought this one a little bit, I don't know if this is the
kind of code you are expecting but I came up with something like that:
generate_transition_matrix <- function(data, n_states) {
#To be sure I imagine you should check n_states is right at this point
transitions <- matrix(0, n_states, n_states)
#we could improve a little bit here because at
2011 Jan 21
2
ordering a vector
Hi,
is there a R function that order a matrix according to some criteria
based on the rows(or cols) of that matrix?
For example, let's say that my matrix S is composed by n rows S_1,
S_2,.., S_n and that I compute some real value g_i=g(S_i) for each
row.
Then I want to order this set of g_i (from smaller to bigger) and
order the correspondent row to the new position.
Is it possible (apart
2009 Sep 11
2
[PATCH] generator.ml: Fix string list memory leak
Parsed string lists are allocated by malloc, but were never freed.
---
src/generator.ml | 16 +++++++++++++++-
1 files changed, 15 insertions(+), 1 deletions(-)
diff --git a/src/generator.ml b/src/generator.ml
index 7571f95..c72c329 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -6320,7 +6320,7 @@ and generate_fish_cmds () =
| OptString n
| FileIn n
|
2011 Aug 26
2
How to generate a random variate that is correlated with a given right-censored random variate?
Hi,
I have a right-censored (positive) random variable (e.g. failure times subject to right censoring) that is observed for N subjects: Y_i, I = 1, 2, ..., N. Note that Y_i = min(T_i, C_i), where T_i is the true failure time and C_i is the censored time. Let us assume that C_i is independent of T_i. Now, I would like to generate another random variable U_i, I = 1, 2, ..., N, which is