Subject: [R] t.test with Welch correction is ambiguous
[External Email]
Dear R Team!
There was an ongoing debate on Research Gate about the "Welch" option in your
base R t.test command. A user noticed that the correction of the degrees of
freedom labeled as "Welch Two Sample
Dear R Team!
There was an ongoing debate on Research Gate about the “Welch” option in
your base R t.test command. A user noticed that the correction of the
degrees of freedom labeled as “Welch Two Sample t-test”, if you choose
var.equal
= TRUE in the R t.test command, differs from the output of
Hi,
I Have two datasets df1 and df2 with 3 matching columns. I need to do a t.test
of sp1, sp2 and sp3� and var1, var2 and var3 where the year, month and location
match.
I can do it with sapply or mapply but I want the end result to be a data.frame.
I prefer to do it with
plyr or dplyr as I have
On Aug 8, 2013, at 6:09 PM, iza.ch1 wrote:
> Hi
>
> I receive a very strange error message after trying to do t-test. When I
> write the code t.test(x) I get an error message: error in t.test(x) :
> function "sqr" not found
>
> I don't understand this problem. Can someone help me how to do i
Hi
I receive a very strange error message after trying to do t-test. When I write
the code t.test(x) I get an error message: error in t.test(x) : function "sqr"
not found
I don't understand this problem. Can someone help me how to do it right?
Thanks a lot :)
On 2010-07-22 11:28, Arne Schulz wrote:
Dear list,
I'd like to do several t-test within a for loop. Example follows:
data1<- rnorm(1:25)
data2<- rnorm(1:25)
vars<- c("data1", "data2")
for (i in vars) {
t.test(i)
}
Unfortunately, it does not work because of the quotes in the vars
Try this:
apply(Vectorize(get)(ls(patt = 'data')), 2, t.test)
On Thu, Jul 22, 2010 at 2:28 PM, Arne Schulz <
arne.sch...@student.uni-kassel.de> wrote:
> Dear list,
> I'd like to do several t-test within a for loop. Example follows:
>
> data1 <- rnorm(1:25)
> data2 <- rnorm(1:25)
> vars <- c("da
On Jul 22, 2010, at 1:28 PM, Arne Schulz wrote:
Dear list,
I'd like to do several t-test within a for loop. Example follows:
data1 <- rnorm(1:25)
data2 <- rnorm(1:25)
vars <- c("data1", "data2")
for (i in vars) {
t.test(i)
}
Unfortunately, it does not work because of the quote
Dear list,
I'd like to do several t-test within a for loop. Example follows:
data1 <- rnorm(1:25)
data2 <- rnorm(1:25)
vars <- c("data1", "data2")
for (i in vars) {
t.test(i)
}
Unfortunately, it does not work because of the quotes in the vars-vector
(running t.test(data1) by hand
On May 5, 2010, at 12:15 PM, Mohamed Lajnef wrote:
Dear All,
I apologize for this trivial question, I can not find the solution
I try to use t.test function per line in the data.frame, But i
dont'understand the error message
my program is as follows
group1<-gl(2,20)
fun<-function(x){
m
Mohamed Lajnef wrote:
Dear All,
I apologize for this trivial question, I can not find the solution
I try to use t.test function per line in the data.frame, But i
dont'understand the error message
my program is as follows
group1<-gl(2,20)
fun<-function(x){
m<-data.frame(group1,x)
#anova(
Dear All,
I apologize for this trivial question, I can not find the solution
I try to use t.test function per line in the data.frame, But i
dont'understand the error message
my program is as follows
group1<-gl(2,20)
fun<-function(x){
m<-data.frame(group1,x)
#anova(aov(x ~ group1, m))
t.est
Marlin -
Consider the following:
df = data.frame(x=rep(1:4,2),y=rep(c('M','F'),c(2,2)))
t.test(x~y,data=df)
Welch Two Sample t-test
data: x by y
t = 4.899, df = 6, p-value = 0.002714
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interva
Hello,
Marlin Keith Cox wrote:
I need a two sample t.test between M and F. The data are arranged in one
column, x. Cant seem to figure how to run a two sample t.test. Not really
sure what this output is giving me, but there should be no difference
between M and F in the example, but summary p
I need a two sample t.test between M and F. The data are arranged in one
column, x. Cant seem to figure how to run a two sample t.test. Not really
sure what this output is giving me, but there should be no difference
between M and F in the example, but summary p-value indicates this.
How can I
Erik Iverson wrote:
See the identical example in ?t.test
I.e., t.test(Score~Group, data=mydata)
parallel to the sleep data example. Actually, that example is
unfortunate, because the sleep data are really paired, not independent
groups.
--
O__ Peter Dalgaard Øster Fa
That typically assumes equal population variances, and not everybody wants
that
in a two-sample test. t.test() provides more options with less work.
Dennis
On Fri, Feb 5, 2010 at 9:38 AM, Jacobs wrote:
>
> I would use aov( )
>
> mod<-aov(Score~Group, data=x)
> summary(mod)
>
> JJ
> --
> View th
I would use aov( )
mod<-aov(Score~Group, data=x)
summary(mod)
JJ
--
View this message in context: http://n4.nabble.com/t-test-tp1470539p1470558.html
Sent from the R help mailing list archive at Nabble.com.
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On Fri, 2010-02-05 at 17:44 +0100, ErikRH wrote:
> Hello! I have a fairly simple (I guess) question. Suppose I have a table
> like this:
>
> Score Group
> 1 Ctrl
> 2 Ctrl
> .......
> 10Treat
> 11Treat
> .. ... ...
> 25Treat
>
> What is(are) t
See the identical example in ?t.test
ErikRH wrote:
Hello! I have a fairly simple (I guess) question. Suppose I have a table
like this:
Score Group
1 Ctrl
2 Ctrl
.......
10Treat
11Treat
.. ... ...
25Treat
What is(are) the simplest command(
Hello! I have a fairly simple (I guess) question. Suppose I have a table
like this:
Score Group
1 Ctrl
2 Ctrl
.......
10Treat
11Treat
.. ... ...
25Treat
What is(are) the simplest command(s) in R to perform an ordinary t-test for
significant d
ricte discussurus
-
-Ursprüngliche Nachricht-
Von: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] Im
Auftrag von Amit Patel
Gesendet: Thursday, July 09, 2009 9:20 AM
An: r-help@r-project.org
Betreff: [R] T.test error help
Hi I am implementing the t
...@r-project.org] Im
Auftrag von Amit Patel
Gesendet: Thursday, July 09, 2009 9:20 AM
An: r-help@r-project.org
Betreff: [R] T.test error help
Hi I am implementing the t.test in a loop and where the data is the same i
get an error message.
Error in t.test.default(Samp3, Samp1, na.rm = TRUE
Hi,
On Jul 9, 2009, at 9:19 AM, Amit Patel wrote:
Hi I am implementing the t.test in a loop and where the data is the
same i get an error message.
Error in t.test.default(Samp3, Samp1, na.rm = TRUE, var.equal =
FALSE, :
data are essentially constant
The script i am using is
for (i i
Hi I am implementing the t.test in a loop and where the data is the same i get
an error message.
Error in t.test.default(Samp3, Samp1, na.rm = TRUE, var.equal = FALSE, :
data are essentially constant
The script i am using is
for (i in 1:length(zz[,1])) {
Samp1 <- zz[i,2:17]
Samp2 <- zz[
Try both of them and see if they jive.
On Mon, Jun 15, 2009 at 6:03 PM, Serebrenik, A. wrote:
> Dear all,
>
> I have two samples that I need to compare. Running Shapiro Wilk normality
> test does not allow me to reject the normality assumption neither for the
> first sample (p-value = 0.8938) no
Dear all,
I have two samples that I need to compare. Running Shapiro Wilk normality test
does not allow me to reject the normality assumption neither for the first
sample (p-value = 0.8938) not for the second one (p-value = 0.07905). So the
t.test seems to be applicable. However, the p-value fo
Hi
r-help-boun...@r-project.org napsal dne 28.01.2009 12:57:55:
> On Wed, 28 Jan 2009, Michael Pearmain wrote:
>
> > Hi All,
> > I've been having a little trouble with creating a loop that will run a
a
> > series of t.tests for inspection,
> > Below is the code i've tried, and some checks i've
On Wed, 28 Jan 2009, Michael Pearmain wrote:
Hi All,
I've been having a little trouble with creating a loop that will run a a
series of t.tests for inspection,
Below is the code i've tried, and some checks i've looked at.
I've used the get(paste()) idea as i was told previously that the use of
Hi All,
I've been having a little trouble with creating a loop that will run a a
series of t.tests for inspection,
Below is the code i've tried, and some checks i've looked at.
I've used the get(paste()) idea as i was told previously that the use of the
eval should try and be avoided.
I've run a
EMAIL PROTECTED]>
> wrote:
>> > I am sure you will get helpful answers. I am almost as sure that you
>> > shouldn't be doing this. I suggest you consult with your local
> statistician.
>> >
>> > -- Bert Gunter
>> >
>> > -O
est you consult with your local
statistician.
> >
> > -- Bert Gunter
> >
> > -Original Message-
> > From: [EMAIL PROTECTED] [
mailto:[EMAIL PROTECTED] On
> > Behalf Of Gang Chen
> > Sent: Thursday, October 02, 2008 11:24 AM
> > To: [EMAIL PROTE
shouldn't be doing this. I suggest you consult with your local statistician.
>
> -- Bert Gunter
>
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of Gang Chen
> Sent: Thursday, October 02, 2008 11:24 AM
> To: [EMAIL PROTECTED]
>
2008 11:24 AM
To: [EMAIL PROTECTED]
Subject: [R] t.test() on a list
I have a list, myList, with each of its 9 components being a 15X15
matrix. I want to run a t-test across the list for each component in
the matrix. For example, the first t-test is on myList[[1]][1, 1],
myList[[2]][1, 1], ..., myLi
I have a list, myList, with each of its 9 components being a 15X15
matrix. I want to run a t-test across the list for each component in
the matrix. For example, the first t-test is on myList[[1]][1, 1],
myList[[2]][1, 1], ..., myList[[9]][1, 1]; and there are totally 15X15
t-tests. How can I run th
Hi Eleni,
Check *"Computing Thousands of Test Statistics Simultaneously in R" *in
http://stat-computing.org/newsletter/v181.pdf
Other alternative could be the multtest package.
HTH
Jorge
On Wed, Mar 5, 2008 at 8:55 AM, Eleni Christodoulou <[EMAIL PROTECTED]>
wrote:
> On Wed, Mar 5, 2008 a
On Wed, Mar 5, 2008 at 2:05 PM, ian white <[EMAIL PROTECTED]> wrote:
> Don't you need to make some allowance for multiple testing? E.g. to get
> a experiment-wise significance level of 0.01 you need
>
> which(p.values < very small number)
>
> where the very small number is approximately 0.01/(tota
I am sorry, the test is unpaired...But my question remains
Thanks,
Eleni
On Wed, Mar 5, 2008 at 2:33 PM, Eleni Christodoulou <[EMAIL PROTECTED]>
wrote:
> Hello list,
>
> I am trying to apply the paired t.test between diseased and not diseased
> patients to identify genes that are more expressed
Hello list,
I am trying to apply the paired t.test between diseased and not diseased
patients to identify genes that are more expressed in the one situation
under the other. In order to retrieve the genes that are more expressed in
the positive disease state I do:
p.values<-c()
for(i in 1:length(S
mogra wrote:
> Hi Thanks for the reply.
>
> I implemented your solution to my problem but ...
>
> For some of my column there is not enough data to do t-test so it gives me
> error and stops the for loop, is any graceful way to check for error msg and
> say ok if there is no $p.value continue t
Hi Thanks for the reply.
I implemented your solution to my problem but ...
For some of my column there is not enough data to do t-test so it gives me
error and stops the for loop, is any graceful way to check for error msg and
say ok if there is no $p.value continue to the next column
Once agai
Am 14.09.2007 um 15:54 schrieb Petr PIKAL:
>> Petr PIKAL wrote:
>>> Hi
>>>
>>> [EMAIL PROTECTED] napsal dne 14.09.2007 13:50:58:
>>>
>>>
Birgit Lemcke wrote:
> Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
>
>
>> S Ellison wrote:
>>
>> Peter Dalgaard <[EMAIL
> Petr PIKAL wrote:
> > Hi
> >
> > [EMAIL PROTECTED] napsal dne 14.09.2007 13:50:58:
> >
> >
> >> Birgit Lemcke wrote:
> >>
> >>> Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
> >>>
> >>>
> S Ellison wrote:
>
> Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16
>>>
> >>
Am 14.09.2007 um 14:27 schrieb Peter Dalgaard:
> Petr PIKAL wrote:
>> Hi
>>
>> [EMAIL PROTECTED] napsal dne 14.09.2007 13:50:58:
>>
>>
>>> Birgit Lemcke wrote:
>>>
Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
> S Ellison wrote:
>
> Peter Dalgaard <[EMAIL PROTECTED
Am 14.09.2007 um 14:12 schrieb Petr PIKAL:
> Hi
>
> [EMAIL PROTECTED] napsal dne 14.09.2007 13:50:58:
>
>> Birgit Lemcke wrote:
>>>
>>> Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
>>>
S Ellison wrote:
>
Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007
09:26:16 >>>
>>>
Petr PIKAL wrote:
> Hi
>
> [EMAIL PROTECTED] napsal dne 14.09.2007 13:50:58:
>
>
>> Birgit Lemcke wrote:
>>
>>> Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
>>>
>>>
S Ellison wrote:
Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16 >>>
Hi
[EMAIL PROTECTED] napsal dne 14.09.2007 13:50:58:
> Birgit Lemcke wrote:
> >
> > Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
> >
> >> S Ellison wrote:
> >>>
> >> Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16 >>>
> >>
> >>>
> >> Yes, but
> >>
> >> I don't think lme(
Birgit Lemcke wrote:
>
> Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
>
>> S Ellison wrote:
>>>
>> Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16 >>>
>>
> So what can I do now to solve my problem?
>
> Do you think I should not use paired=TRUE?
>
You *can* only
Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
> S Ellison wrote:
>>
> Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16 >>>
>
So what can I do now to solve my problem?
Do you think I should not use paired=TRUE?
>>> You *can* only use it when you have pairs, and y
S Ellison wrote:
>
Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16 >>>
>>> So what can I do now to solve my problem?
>>>
>>> Do you think I should not use paired=TRUE?
>>>
>> You *can* only use it when you have pairs, and you must do it then, to
>> correct for in
>>> Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16 >>>
>> So what can I do now to solve my problem?
>>
>> Do you think I should not use paired=TRUE?
>You *can* only use it when you have pairs, and you must do it then, to
>correct for intra-pair correlation. The drawback is that it looks o
Am 14.09.2007 um 10:26 schrieb Peter Dalgaard:
> Birgit Lemcke wrote:
>> Thanks for your answer.
>>
>> First I will show you both vectors:
>> [...]
>>
>> I tried this (complete.cases(Fem66, Mal66)) and you are right, it
>> gives me back:
>>
>> (complete.cases(Fem66, Mal66))
>> [1] FALSE FALSE
Birgit Lemcke wrote:
> Thanks for your answer.
>
> First I will show you both vectors:
> [...]
>
> I tried this (complete.cases(Fem66, Mal66)) and you are right, it
> gives me back:
>
> (complete.cases(Fem66, Mal66))
> [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
> FALSE FALS
Thanks for your answer.
First I will show you both vectors:
Mal66
[1] NA NA NA NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
[28] NA NA NA NA NA NA NA NA NA NA NA NA
NA NA NA NA
Birgit Lemcke wrote:
> Hello!
>
> I am using R 2.5.1 on a Apple Power Book G4 with Mac OS X 10.4.10 and
> I am still R beginner.
>
> I try to calculate a t.test() using this code:
>
> TTest75<-t.test(Fem75, Mal75, alternative= "two.sided", paired= TRUE)
>
> This works properly, but I have t
Hello!
I am using R 2.5.1 on a Apple Power Book G4 with Mac OS X 10.4.10 and
I am still R beginner.
I try to calculate a t.test() using this code:
TTest75<-t.test(Fem75, Mal75, alternative= "two.sided", paired= TRUE)
This works properly, but I have two variables with a lot of missing
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