Displaying 20 results from an estimated 3000 matches similar to: "how to compute p-value?"
2007 Jun 19
2
Preconditions for a variance analysis
Hello everbody,
i'm currently using the anova()-test for a small data.frame of 40
rows and 2 columns. It works well, but is there any preconditions for
a valid variance analysis, that i should consider?
Thank you for your answer,
Daniel
2006 May 11
1
t-test with autocorrelation correction
Has anyone implemented a t-test with the effective sample size
correction proposed by Dale and Fortin, Ecoscience 9(2):162-167, 2002,
using a discussion by Cressie, 1993, page 15?
thanks,
Denis
2006 Nov 06
2
comparing 2 dataframes
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2007 Jan 03
1
mathematical symbols in plots
Hello everyone!
I'm trying to plot some mathematical expression along my axis, but
demo(plotmath) did not have the symbol I was looking for. In particular,
I would like to denote the mean of an observable by writing
<k>
which I tried to enter with
expression(group("<", k, ">"))
However, my naive try doesn't work and the help doesn't want to tell me,
2007 Jun 16
1
Lines connecting the boxes in a boxplot
Hello,
I'm currently using a boxplot to visualize data for three different
models. As I have three models, I'm plotting three parallel boxplots
for each factor.
This works fine - what I need now is a line connecting the medians of
each boxplot of each model. I want to do this in order to visualize
the trend that one of the models exhibit. Basically, I want to plot a
curve for each model
2007 Feb 27
1
prop.test or chisq.test ..?
Hi everyone,
Suppose I have a count the occurrences of positive results, and the total
number of occurrences:
pos <- 14
total <- 15
testing that the proportion of positive occurrences is greater than 0.5 gives
a p-value and confidence interval:
prop.test( pos, total, p=0.5, alternative='greater')
1-sample proportions test with continuity correction
data: 14 out of
2006 Sep 22
2
Merge problem
Hello all,
I have read as many merge issues as I possibly could tonight and
although I presume this is a small error, I have not found the
solution to my problem.
I'm trying to merge two data sets: dat0 and TransTable. As you can
see below, dat0 has 8000 rows, whereas TransTable has 47296 rows. I
would expect when I merge the two data sets, with all.x=F, and
all.y=F, that the
2007 Jan 23
3
the value of Delta
Dear all,
I am running R 2.4.1.
> library(siggenes);
> library(multtest);
> cl<-rep(c(0,1),c(3,3));
> sub<-exprs(AffyExpData[,c(1:3,7:9)]);
> gn<-geneNames(AffyRAwData);
> sam.out<-sam(sub,cl,rand=123,gene.names=gn);
We're doing 20 complete permutations
> sam.out
SAM Analysis for the Two-Class Unpaired Case Assuming Unequal Variances
Delta p0
2007 Jun 12
2
Data transformation for chi-square test.
Dear all R users
:
I am a IT student with few statistical background and new R user for only
have two month exprience. I have a data named medcost, import by
read.table() as follow for example (real dataset has 500 cases), the
heander id means case id, member means members in a family and cost is the
family pay for medical cost every 6 months.
id member cost
1 4
2007 Jan 20
1
aov y lme
Dear R user,
I am trying to reproduce the results in Montgomery D.C (2001, chap 13,
example 13-1).
Briefly, there are three suppliers, four batches nested within suppliers
and three determinations of purity (response variable) on each batch. It is
a two stage nested design, where suppliers are fixed and batches are random.
y_ijk=mu+tau_i+beta_j(nested in tau_i)+epsilon_ijk
Here are the
2006 Nov 07
3
question on multilevel modeling
Hi,
I am trying to run a multilevel model with time nested in people and
people nested in dyads (3 levels of nesting) by initially running a
series of models to test whether the slope/intercept should be fixed or
random. The problem that I am experiencing appears to arise between the
random intercept, fixed slope equation AND.
(syntax:
rint<-lme(BDIAFTER~BDI+WEEK+CORUMTO,
2005 May 15
3
adjusted p-values with TukeyHSD?
hi list,
i have to ask you again, having tried and searched for several days...
i want to do a TukeyHSD after an Anova, and want to get the adjusted
p-values after the Tukey Correction.
i found the p.adjust function, but it can only correct for "holm",
"hochberg", bonferroni", but not "Tukey".
Is it not possbile to get adjusted p-values after
2006 Mar 15
2
difftime arguments
Hi
I just started using RGui.exe under widnows.
I have a text file containing date arranged in columns and rows, each column has the same format, each row with different formats. 3 of the columns are something like this 1/12/2006 3:59:45 PM
I need to calculate the different in seconds between 2 selected periods using their row’s index
My solution:
Read the file in a data frame and
2006 Feb 04
1
Mixed models and missing p-value...
Dear R-users,
I computed a simple mixed models which was:
mod<-lmer(nb ~ site + (1|patelle),tr)
The output was:
Linear mixed-effects model fit by REML
Formula: nb ~ site + (1 | patelle)
Data: tr
AIC BIC logLik MLdeviance REMLdeviance
1157.437 1168.686 -574.7184 1164.523 1149.437
Random effects:
Groups Name Variance Std.Dev.
patelle
2006 Sep 25
1
apply: new behaviour for factors in R-2.4.0
Dear R-core
There is a different output for the apply function due to the
change of unlist as mentioned in the R news.
Newly, applying as.factor() (or factor()) in
str(dat <- data.frame(x = 1:10, f1 = gl(2,5,labels = c("A", "B"))))
(d1 <- apply(dat,2,as.factor))
newly returns a character matrix while in R-2.3.1 the same
command resulted in an integer matrix that was
2006 Apr 25
1
summary.lme: argument "adjustSigma"
Dear R-list
I have a question concerning the argument "adjustSigma" in the
function "lme" of the package "nlme".
The help page says:
"the residual standard error is multiplied by sqrt(nobs/(nobs -
npar)), converting it to a REML-like estimate."
Having a look into the code I found:
stdFixed <- sqrt(diag(as.matrix(object$varFix)))
if (object$method
2005 Aug 02
1
plotting 3 functions on same graph
hi all,
I wish to draw on the same graphic device 3 functions.
But i don't want them to be on different graph, i want to compare them on the same
I don't need mfrow or mfcol, I need something else...
1 graph on 1 device inside this graph 3 ploted function.
I saw something unsing data.frame, but i think it's overkill, and something less complicated must exist, if not why?
why not
2006 Jan 30
2
Type II SS for fixed-effect in mixed model
Hi
In mixed-model with lme()
How can I obtain Type II SS or Type III SS for fixed effect?
Thanks
Julien
2006 Feb 01
1
Randomised Block Design
Hi, I'm studying math, and i have to make an analysys using Randomised
Block Design. I have two factors, i know how to do this in Statistica, but
how to do this in R, i read some manuals but the only thing that i have
found was 2 factor ANOVA.
Please could someone help me, or give some usefull links ??
Krzytsztof Suwada
2006 Feb 20
1
Extracting variance components from lmer
Hi All.
I need a bit of help extracting the residual error variance from the VarCorr
structure from lmer.
#Here's a 2-way random effects model
lmer.1 <- lmer(rating ~ (1|person)+(1|rater), data = dat)
#Get the structure
vc.fit <- VarCorr(lmer.1)
#results in.....
$person
1 x 1 Matrix of class "dpoMatrix"
(Intercept)
(Intercept) 0.7755392
$rater
1 x 1 Matrix