Displaying 20 results from an estimated 3000 matches similar to: "Random intercept model with time-dependent covariates, results different from SAS"
2007 Jan 19
4
Newbie question: Statistical functions (e.g., mean, sd) in a "transform" statement?
Greetings listeRs -
Given a data frame such as
times
time1 time2 time3 time4
1 70.408543 48.92378 7.399605 95.93050
2 17.231940 27.48530 82.962916 10.20619
3 20.279220 10.33575 66.209290 30.71846
4 NA 53.31993 12.398237 35.65782
5 9.295965 NA 48.929201 NA
6 63.966518 42.16304 1.777342 NA
one can use "transform" to
2012 Nov 30
1
help on "stacking" matrices up
Dear All,
#I have the following code
Dose<-1000
Tinf <-0.5
INTERVAL <-8
TIME8 <-matrix(c((0*INTERVAL):(1*INTERVAL)))
TIME7 <-matrix(c((0*INTERVAL):(2*INTERVAL)))
TIME6 <-matrix(c((0*INTERVAL):(3*INTERVAL)))
TIME5 <-matrix(c((0*INTERVAL):(4*INTERVAL)))
TIME4 <-matrix(c((0*INTERVAL):(5*INTERVAL)))
TIME3 <-matrix(c((0*INTERVAL):(6*INTERVAL)))
TIME2
2010 May 20
1
Strange behaviour when using diff with POSIXt and POSIXlt objects
Dear list,
I´m calculating time differences between series of time stamps and I noticed
something odd:
If I do this...
> time1=strptime("2009 05 31 22 57 00",format="%Y %m %d %H %M")
> time2=strptime("2009 05 31 23 07 00",format="%Y %m %d %H %M")
>
> diff(c(time1,time2),units="mins")
Time difference of 10 mins
.. I get the correct
2005 Nov 15
1
Repeates Measures MANOVA for Time*Treatment Interactions
Dear R folk,
First off I want to thank those of you who responded with comments for
my R quick and dirty stats tutorial. They've been quite helpful, and
I'm in the process of revising them. When it comes to repeated
measures MANOVA, I'm in a bit of a bind, however. I'm beginning to see
that all of the documentation is written for psychologists, who have a
slightly
2005 Aug 10
2
Treatment-response analysis along time
Dear R people,
I wonder if you could give me a hand with some of my data. I have a very
typical analysis in biology, however it is difficult for me to find the
right way to analyse. I had a group of animals, I gave them a treatment, and
I measure a variable along time -one??s per day- along 5 days,for
example(fake data):
Animals Time1 Time2 Time3 Time4
1 1 5 3
2012 Mar 28
3
Connect lines in a dot plot on a subject-by-subject basis
I am trying to plot where data points from a give subject are connected by a line. Each subject is represented by a single row of data. Each subject can have
up to five observations. The first five columns of mydata give the time of observation, columns 6-10 give the values at each time point. Some subjects have
all data, some are missing values.
The code I wrote to draw the plot is listed below.
2011 May 01
1
Mean/SD of Each Position in Table
I have 100+ .csv files which have the basic format:
> test
X Substance1 Substance2 Substance3 Substance4 Substance5
1 Time1 10 0 0 0 0
2 Time2 9 5 0 0 0
3 Time3 8 10 1 0 0
4 Time4 7 20 2 1 0
5 Time5
2007 May 13
2
Some questions on repeated measures (M)ANOVA & mixed models with lme4
Dear R Masters,
I'm an anesthesiology resident trying to make his way through basic
statistics. Recently I have been confronted with longitudinal data in
a treatment vs. control analysis. My dataframe is in the form of:
subj | group | baseline | time | outcome (long)
or
subj | group | baseline | time1 |...| time6 | (wide)
The measured variable is a continuous one. The null hypothesis in
2007 Dec 16
4
improving a bar graph
Hello,
Below is the code for a basic bar graph. I was seeking advice
regarding the following:
(a) For each time period there are values from 16 people. How I can
change the colour value so that each person has a different colour,
which recurs across each of the three graphs/tie epriods?
(b) I have seen much more sophisticated examples using lattice (e.g
each person has a separate
2004 Aug 05
1
Post-hoc t-tests in 2-way repeated measure ANOVA
Hi all
I am running a 2-way repeated measure anova with 1 between-subjects
factor (Group=treatment, control), and 1 within-subject factor (Time of
measurement: time1, time2). I extract the results of the anova with:
summary(aov(effect ~ Group*Time + Error=Subj/Time, data=mydata))
Now, this must be clearly a dumb question, but how can I quickly extract
in R all the post-hoc t-tests for the
2011 Aug 17
1
contrast package with interactions in gls model
Hi!
I try to explain the efffect of (1) forest where i took samples's soils (*
Lugar*: categorical variable with three levels), (2) nitrogen addition
treatments (*Tra*: categorical variable with two levels) on total carbon
concentration's soil samples (*C: *continue* *variable) during four months
of sampling (*Time:* categorical and ordered variable with four levels).
I fitted the
2012 Apr 15
2
xyplot type="l"
Probably a stupidly simple question, but I wouldn't know how to google it:
xyplot(neuro ~ time | UserID, data=data_sub)
creates a proper plot.
However, if I add
type = "l"
the lines do not go first through time1, then time2, then time3 etc but in
about 50% of all subjects the lines go through points seemingly random
(e.g. from 1 to 4 to 2 to 5 to 3).
The lines always start at time
2008 Oct 29
2
call works with gee and yags, but not geepack
I have included data at the bottom of this email. It can be read in by
highlighting the data and then using this command: dat <-
read.table("clipboard", header = TRUE,sep="\t")
I can obtain solutions with both of these:
library(gee)
fit.gee<-gee(score ~ chem + time, id=id,
family=gaussian,corstr="exchangeable",data=dat)
and
library(yags)
fit.yags <-
2016 Dec 08
3
wish list: generalized apply
Dear All,
I regularly want to "apply" some function to an array in a way that the arguments to the user function depend on the index on which the apply is working. A simple example is:
A <- array( runif(160), dim=c(5,4,8) )
x <- matrix( runif(32), nrow=4, ncol=8 )
b <- runif(8)
f1 <- function( A, x, b ) { sum( A %*% x ) + b }
result <- rep(0.0,8)
for (i in 1:8) {
2010 Jul 16
1
Nested if help
Hello,
I am trying to find a direct way to write a nested if of sorts to find data
for a specific time range for a specific day (across a range of days) and
have exhausted my abilities with the manuals I have at hand. I have a good
deal of data of this approximate form:
day time price
1 1am 5
1 2am 7
1 3am 9
1 4am 12
2 1am 5
2 2am 7
2
2009 May 15
13
How to calculate java method timestamp?
Hi,
I need help in calculating Java method time-stamp in following fashion.
Consider following method example.
long method3(long stop) {
try {
Thread.sleep(1500);
} catch (Exception e) {
}
//////////////////// real CPU intensive operation ///////////////////////////
for (int i = 1; i < stop; i++) {
stop = stop * stop * i;
};
2011 Nov 10
2
performance of adaptIntegrate vs. integrate
Dear list,
[cross-posting from Stack Overflow where this question has remained
unanswered for two weeks]
I'd like to perform a numerical integration in one dimension,
I = int_a^b f(x) dx
where the integrand f: x in IR -> f(x) in IR^p is vector-valued.
integrate() only allows scalar integrands, thus I would need to call
it many (p=200 typically) times, which sounds suboptimal. The
2010 Nov 15
3
merge two dataset and replace missing by 0
Hi r users,
I have two data sets (X1, X2). For example,
time1<-c( 0, 8, 15, 22, 43, 64, 85, 106, 127, 148, 169, 190 ,211 )
outpue1<-c(171 ,164 ,150 ,141 ,109 , 73 , 47 ,26 ,15 ,12 ,6 ,2 ,1 )
X1<-cbind(time1,outpue1)
time2<-c( 0 ,8 ,15 , 22 ,43 , 64 ,85 ,106 ,148)
output2<-c( 5 ,5 ,4 ,5 ,5 ,4 ,1 ,2 , 1 )
X2<-cbind(time2,output2)
I want to
2008 Apr 09
2
fuzzy merge
Hi,
I would like to merge two data frames. It is just that I want the merging to be done with some kind of a fuzzy criterion. Let me explain.
My first data frame looks like this :
ID1 time1 dt
1 2008-01-02 13:11 10
2 2008-01-02 14:20 20
3
2010 Sep 02
2
date
Hello all,
I've 2 strings that representing the start and end values of a date and
time.
For example,
time1 <- c("21/04/2005","23/05/2005","11/04/2005")
time2 <- c("15/07/2009", "03/06/2008", "15/10/2005")
as.difftime(time1,time2)
Time differences in secs
[1] NA NA NA
attr(,"tzone")
[1] ""
How can i