Displaying 20 results from an estimated 10000 matches similar to: "Find if there is independence"
2007 Nov 22
5
testing independence of categorical variables
hi,
is there a way of calculating of measuring dependence between two
categorical variables. i tried using the chi square test to test for
independence but i got error saying that the lengths of the two
vectors don't match. Suppose X and Y are two factors. X has 5 levels
and Y has 7 levels. This is what i tried doing
>temp<-chisq.test(x,y)
but got error "the lengths of the two
2012 Dec 01
4
Getting all possible contingency tables
Hello all,
Let say I have 2-way contingency table:
Tab <- matrix(c(8, 10, 12, 6), nr = 2)
and the Chi-squared test could not reject the independence:
> chisq.test(Tab)
Pearson's Chi-squared test with Yates' continuity correction
data: Tab
X-squared = 1.0125, df = 1, p-value = 0.3143
However I want to get all possible contingency tables under this
independence
2012 Jun 26
5
chisq.test
Dear list!
I would like to calculate "chisq.test" on simple data set with 70 observations, but the output is ''Warning message:''
Warning message:
In chisq.test(tabele) : Chi-squared approximation may be incorrect
Here is an example:
tabele <- matrix(c(11, 3, 3, 18, 3, 6, 5, 21), ncol = 4, byrow = TRUE)
dimnames(tabela) <- list(
2005 Dec 20
2
2 x 2 chisq.test (PR#8415)
Full_Name: nobody
Version: 2.2.0
OS: any
Submission from: (NULL) (219.66.34.183)
2 x 2 table, such as
> x
[,1] [,2]
[1,] 10 12
[2,] 11 13
> chisq.test(x)
Pearson's Chi-squared test with Yates'
continuity correction
data: x
X-squared = 0.0732, df = 1, p-value = 0.7868
but, X-squared = 0.0732 is over corrected.
when abs(a*d-b*c) <= sum(a,b,c,d), chisq.value
2003 Jun 13
2
formula (joint, conditional independence, etc.) - mosaicplots
Hi,
Can someone set me straight as to how to write formulas in R to indicate:
complete independence [A][B][C]
joint independence [AB][C]
conditional independence [AC][BC]
nway interaction [AB][AC][BC]
?
For example, if I have 4 factors:
hair colour, eye colour, age, sex
does
> mosaicplot( frequency ~ hair + eye + age + sex)
mean that the model fitted is of complete independence of
2005 Jun 22
1
chisq test and fisher exact test
Hi,
I have a text mining project and currently I am working on feature
generation/selection part.
My plan is selecting a set of words or word combinations which have
better discriminant capability than other words in telling the group
id's (2 classes in this case) for a dataset which has 2,000,000
documents.
One approach is using "contrast-set association rule mining" while the
2005 Oct 30
4
Yates' correction for continuity in chisq.test (PR#8265)
Full_Name: foo ba baz
Version: R2.2.0
OS: Mac OS X (10.4)
Submission from: (NULL) (219.66.32.183)
chisq.test(matrix(c(9,10,9,11),2,2))
Chi-square value must be 0, and, P value must be 0
R does over correction
when | a d - b c | < n / 2 ,chi-sq must be 0
2011 Apr 22
1
Create 2x2 table from summary data and run chi square test.
R 2.12
windows 7
I am summary data that I would like to make into a 2x2 table representing counts positive vs. negative counts:
28/289 20/276
My table should look something like the following:
group1 group2
Positive 28 20
Negative 289 276
How can a (1) create the 2x2 table
(2) run a chi square test on the table?
I have tried the following code, but I
2004 Oct 09
2
Is it safe? Cochran etc
I have the following contingency table
dat <- matrix(c(1,506,13714,878702),nr=2)
And I want to test if their is an association between events
A:{a,not(a)} and B:{b,not(b)}
| b | not(b) |
--------+-----+--------+
a | 1 | 13714 |
--------+-----+--------+
not(a) | 506 | 878702 |
--------+-----+--------+
I am worried that prop.test and chisq.test are not valid given the
2012 Dec 03
4
Chi-squared test when observed near expected
Dear UseRs,
I'm running a chi-squared test where the expected matrix is the same as the
observed, after rounding. R reports a X-squared of zero with a p value of
one. I can justify this because any other result will deviate at least as
much from the expected because what we observe is the expected, after
rounding. But the formula for X-squared, sum (O-E)^2/E gives a positive
value. What
2008 Mar 28
2
Comparing proportions between groups
Hello there,
I have two groups (men and women) and I know per group how many of them
smoke or don't smoke (women 40 of 200; men 100 of 300). I would like to know
how I can compare in R if men and women differ significantly in their
smoking. However, because there are more men in the sample than women I
cannot just compare the number of smokers and non-smokers in both groups,
right?! (I would
2001 Dec 18
4
chi-squared test
I don't quite understand the difference between the two methods for
performing a chi-squared test on contingency tables: summary(table())
and chisq.test()
They may different results. E.g.:
aa <- gl(2, 10)
bb <- as.factor(c(1,2,2,2,1,2,1,2,2,2,1,2,2,2,1,1,1,2,1,1))
aa <- c(aa, aa)
bb <- c(bb, bb)
table(aa, bb)
summary(table(aa, bb))
chisq.test(aa, bb)
Could somebody give me
2002 Apr 12
2
Help
I have an adjacency matrix and I want to obtain a matrix of the minimum
paths between the nodes. Thank you
Alessandro Ambrosini
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2012 Jan 30
1
Visual Basic game
I'm trying to launch a visual basic game,i have all the neccesery libraries installed. On launch i get this
Code:
err:ntdll:RtlpWaitForCriticalSection section 0x7bcbf8e0 "../../../wine/dlls/ntdll/loader.c: loader_section" wait timed out in thread 003c, blocked by 0034, retrying (60 sec)
err:ntdll:RtlpWaitForCriticalSection section 0x78037130 "?" wait timed out in thread
2005 Jun 26
2
chisq.test using amalgamation automatically (possible ?!?)
Dear List,
If any of observed and/or expected data has less than
5 frequencies, then chisq.test (Pearson's Chi-squared
Test for Count Data from package:stats) gives warning
messages. For example,
x<-c(10, 14, 10, 11, 11, 7, 8, 4, 1, 4, 4, 2, 1, 1, 2,
1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1)
y<-c(9.13112391745095, 13.1626482033341,
12.6623267638188, 11.0130706413029, 9.16415925139016,
2002 Apr 15
6
two questions
The first: if I have a vector as (1,1,3,2,1,1), which is the command that
gives all the positions of the min value? From the vector of the example a
would like to obtain a new vector as (1,2,5,6) that give me all the
positions of the minimum value 1.
The second: if I have a matrix "A" and I want to obtain a new matrix
deleting a column or a row of A, what have I to do?
Thank you.
2011 Dec 19
2
On Corrections for Chi-Sq Goodness of Fit Test
TOPIC
My question regards the philosophy behind how R implements corrections to chi-square statistical tests. At least in recent versions (I'm using 2.13.1 (2011-07-08) on OSX 10.6.8.), the chisq.test function applies the Yates continuity correction for 2 by 2 contingency tables. But when used as a goodness of fit test (GoF, aka likelihood ratio test), chisq.test does not appear to implement
2002 Jul 30
4
chisq.test, basic question
The cells are interpreted as counts, so by scaling you're analyzing a
different experiment (one with fewer observations). So the chi-squared value
will change (the terms (O-E)^2/E in the statistic scale linearly ignoring
rounding and "Yates' continuity correction").
The chisq.test on the original data is a test of association. Conventionally
you decide ahead of time on a
2002 Apr 18
5
Two problems
Hello! Two questions:
1: I have to import a matrix of adjacency from a file of a software that is
not R (for example "bloc notes" of Windows). The problem is that the matrix
is not in the explicit form as
0 1 1
1 0 0
1 0 0
but it is a scattered matrix where in each row there are two nodes that have
a direct path.
The matrix is
a b
a c
b a
c a
For example, the first row
2002 Apr 30
3
A sample question
Hello.
Given a vector 1 3 4 2 8 9 5
I want to obtain a vector with all 0 except in the second position and in
the fifth, where the numbers are the same of the first vector.
The new vector must be
0 3 0 0 8 0 0
Thank you very much.
Excuseme but my mind is out of order.
Alessandro
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