Displaying 20 results from an estimated 1000 matches similar to: "chi-Squared distribution"
2005 Jan 21
2
chi-Squared distribution in Friedman test
Dear R helpers:
Thanks for the previous reply. I am using Friedman racing test. According the the book "Pratical Nonprametric Statistic" by WJ Conover, after computing the statistics, he suggested to use chi-squared or F distribution to accept or reject null hypothesis. After looking into the source code, I found that R uses chi-sqaured distribution as below:
PVAL <-
2005 Jan 21
0
R: chi-Squared distribution
Hi,
Attention chi-squared distribution, unlike F
distribution, has only df1 as parameter, not df1 and
df2. So correct into:
outer(1:3, 1:3, function(df1, df2) qchisq(0.95, df1,
df2))
outer(1:3, 1:3, function(df1, df2) qchisq(0.95, df1))
^^^^^^^^^^^^^^^^^^^^
Regards,
Vito
you wrote:
Dear Rs:
outer(1:3, 1:3, function(df1, df2) qf(0.95, df1, df2))
I compare this F
2005 Nov 25
1
Plotting the diff. between two curves
Dear Rs
I have two vectors A and B
where
A is
V1 d
1 0.000100000 1.123278
2 0.002186431 1.120448
3 0.004351214 1.106661
4 0.006515998 1.107713
5 0.008680781 1.107667
6 0.013010348 1.106353
7 0.019504698 1.104077
8 0.034658181 1.103202
9 0.051976447 1.103200
10 0.073624280 1.094825
11 0.093085682 1.085123
12 0.095250465 1.087325
13 0.132051782 1.086158
14 0.168853098
2005 Nov 03
1
Help in expand.grid() (Restricted combination)
Dear Rs:
BY having the following code:
candidates<-expand.grid(e=c("nearest-neighbor","exaustive"),
d=c(70,75,80,85,90,92,94,96,98,99),
n=c(20,25,30,35,40))
results in :
e d n
1 nearest-neighbor 70 20
2 exaustive 70 20
3 nearest-neighbor 75 20
4 exaustive 75 20
................
90 exaustive 90 40
91 nearest-neighbor 92 40
92 exaustive 92 40
93 nearest-neighbor 94 40
94
2006 Feb 17
2
Grouping and Averaging in Table
Dear Rs
I have a single table with three columns in the following form:
1 100 150
1 45 32
1 99 100
2 150 33
2 22 87
2 71 31
....
....
1000 64 32
1 100 150
1 45 32
1 99 100
2 22 89
2 31 44
2 88 11
....
....
1200 64 32
1 100 150
1 45 32
1 99 100
2 150 33
2 22 87
2 71 31
...
...
1100 31 34
Totally 1000+1200+1100 rows. Now, I need to group by first column
and average then second and third column
2006 Mar 11
1
Scaling in plot function
Dear R helpers,
I have a vector of 500 numbers and I need to plot them in such a way
that the first 250 values should occupy 80% of the plot and the
remaining ones should take 20%. More precisely, x axis ranges form
1:500 and the idea is to give the snapshot of the first 250 values. I
tried "axis()" and log="x", but I am not getting the required output.
Thanks
2008 Jan 07
2
chi-squared with zero df (PR#10551)
Full_Name: Jerry W. Lewis
Version: 2.6.1
OS: Windows XP Professional
Submission from: (NULL) (24.147.191.250)
pchisq(0,0,ncp=lambda) returns 0 instead of exp(-lambda/2)
pchisq(x,0,ncp=lambda) returns NaN instead of exp(-lambda/2)*(1 +
SUM_{r=0}^infty ((lambda/2)^r / r!) pchisq(x, df + 2r))
qchisq(.7,0,ncp=1) returns 1.712252 instead of 0.701297103
qchisq(exp(-1/2),0,ncp=1) returns 1.238938
2005 Jan 21
0
R: chi-Squared distribution in Friedman test
Hi,
pchisq -> distribution function
dchisq -> density function
pval is the area under the curve, to calculte it you
use distribution function which is the integral of
density function. See:
http://www.itl.nist.gov/div898/handbook/eda/section3/eda362.htm
http://mathworld.wolfram.com/DistributionFunction.html
f(x) density function
F(x) distribution function =Pr(X<x)= integral(f(x))
2008 Nov 07
4
chi square table
Hi,
How do we get the value of a chi square as we usually look up on the
table on our text book?
i.e. Chi-square(0.01, df=8), the text book table gives 20.090
> dchisq(0.01, df=8)
[1] 1.036471e-08
> pchisq(0.01, df=8)
[1] 2.593772e-11
> qchisq(0.01, df=8)
[1] 1.646497
>
nono of them give me 20.090
Thanks,
cruz
2017 Dec 18
2
chi-square distribution table
Please could you tell me how to make code to make chi-square
distribution table?
Please help
2004 Mar 10
1
accuracy of chi-square distribution approximations
Hi there,
How accurate is the aproximation R makes to the Chi-Square distribution?
For example, if I run:
> qchisq(1/1000000,6)
[1] 0.03650857
how accurate is 0.0365 compared to the theoretical percentile? What kind
of approximations have been made in the software's algorithm? It woudl be
useful to know since I am working with tiny percentiles such as one
one-millionth and one
2006 Nov 02
6
Multiple items in the where clause while updating...
Hi
The following is a database table named friends.
+-----+------+------+-------+
| sid | id | fid | ftype |
+-----+------+------+-------+
| 30 | 1 | 2 | F |
| 31 | 1 | 3 | R |
| 32 | 3 | 2 | F |
| 33 | 3 | 4 | F |
+-----+------+------+-------+
I want to update the ftype field based on id and fid.
I want to achive the following.
Update friends
2007 Jan 22
1
Latin hyper cube sampling from expand.grid()
Dear R experts
I am looking for a package which gives me latin hyper cube samples
from the grid of values produced from the command "expand.grid". Any
pointers to this issue might be very useful. Basically, I am doing the
following:
> a<-(1:10)
> b<-(20:30)
> dataGrid<-expand.grid(a,b)
Now, is there a way to use this "dataGrid" in the package
2017 Sep 13
0
glusterfs expose iSCSI
On Wed, Sep 13, 2017 at 1:03 PM, GiangCoi Mr <ltrgiang86 at gmail.com> wrote:
> Hi all
>
Hi GiangCoi,
The Good news is that now we have gluster-block [1] which will help
you configure block storage using gluster very easy.
gluster-block will take care of all the targetcli and tcmu-runner
configuration for you, all you need as a pre-requisite is a gluster
volume.
And the sad part is
2005 Jun 15
1
Chi square convolution?
Hi,
I want to determine the confidence interval on the sum of two sigma's.
Is there an easy way to do this in R? I guess I have to use some sort of
chisquare convolution algorithm???
Thanx,
Roy
--
The information contained in this communication and any atta...{{dropped}}
2009 Oct 11
2
Accuracy (PR#13999)
Full_Name: Viktor Witkovsky
Version: 2.9.2
OS: Windows XP
Submission from: (NULL) (78.98.89.227)
Hello,
I have found strange behavior of the function qchisq (the non-central qchisq is
based on inversion of pchisq, which is further based on pgamma). The function
gives wrong results without any warning. For example:
qchisq(1e-12,1,8.94^2,lower.tail=FALSE) gives 255.1840972465858 (notice that
2005 Aug 26
3
Matrix oriented computing
Hi,
I want to compute the quantiles of Chi^2 distributions with different
degrees of freedom like
x<-cbind(0.005, 0.010, 0.025, 0.05, 0.1, 0.5, 0.9, 0.95, 0.975, 0.99, 0.995)
df<-rbind(1:100)
m<-qchisq(x,df)
and hoped to get back a length(df) times length(x) matrix with the
quantiles. Since this does not work, I use
x<-c(0.005, 0.010, 0.025, 0.05, 0.1, 0.5, 0.9, 0.95, 0.975,
2004 Sep 06
1
qchisq (PR#7212)
Full_Name: David Clayton
Version: 1.8.1
OS: Linux
Submission from: (NULL) (131.111.126.242)
qchisq behaves very strangely when ncp is passed as zero (forcing internal
qnchisq to be called) when first argument is small.
Eg
> qchisq(1-1e-6, 1, ncp=0, lower.tail=TRUE)
qchisq(1-1e-6, 1, ncp=0, lower.tail=TRUE)
[1] 1024
while, if ncp is unspecified,
> qchisq(1-1e-6, 1)
qchisq(1-1e-6, 1)
2004 Jan 19
2
small bug on qchisq (PR#6442)
Full_Name: Drouilhet R?my
Version: 1.8.1
OS: Linux
Submission from: (NULL) (195.221.43.136)
qchisq(1,10) works well but qchisq(1,10,ncp=0) does not work whereas ncp=0 is
the default value of the function qchisq(1,10). (of course, 10 will be replaced
by any integer value).
Let us notice that this bug occurs only when applying probability one.
(qchisq(seq(0,.9,.1),10,ncp=0) works very well).
2006 Apr 10
2
Legend in the outer margin
Dear Rs
I have a 3x3 multiple plot. I would like to have a overall legend in
the outer right margin.
From the help archive, I found that it can be done by setting
par(xpd=NA). However, I couldn't find the correct values
for x and y co-ordinates for the legend. Please find the code snippet below:
par(mfrow=c(3,3), mar=c(4,4,0.9,0.5), oma=c(1,2,2,4),cex.main=1.1)