[R] exact trend test
dwinsemius at comcast.net
Thu Jan 7 08:31:14 CET 2016
> On Jan 6, 2016, at 8:16 PM, li li <hannah.hlx at gmail.com> wrote:
> Hi all,
> Is there an R function that does exact randomization trend test?
> For example, consider the 2 by 5 contingency table below:
> dose0 dose 0.15 dose 0.5 dose 1.5 dose 5 row
> Yes 4 3 4 5
> 8 24
> No 4 5 4 3
> 0 16
> col sum 8 8 8 8
> 8 40
Your data presentation has been distorted by your failure to post in plain text. Surely you have been asked in the past to correct this issue?
> To do the exact trend test, we need to enumerate all the contingency table
> with the
> row and column margins fixed.
Er, how should that be done? A trend test? What is described above would be a general test of no association rather than a trend test. Please use clear language and be as specific as possible if you choose to respond.
> Find the probability corresponding to
> the corresponding contingency tables based on the multivariate
> hypergeometric distribution. Finally the pvalue is obtained by adding
> relevant probabilities.
If there is a trend under consideration, then I do not understand such a trend would be modeled under a hypergeometric distribution? A hypergeometic distribution would suggest no trend, at least to my current understanding.
> Is there an R function that does this? if not, I am wondering whether it is
> possible to
> enumerate all possible contingency tables that has column sun and row sum
Wel, yes, that is possible and routinely done with `fisher.test`, but it is up to you to describe how that activity leads to a trend test.
If you assume Poisson distributed errors a trend test is fairly easy to construct with glm.
> Thanks very much!!
> [[alternative HTML version deleted]]
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Alameda, CA, USA
More information about the R-help