Getting all possible contingency tables
On Dec 1, 2012, at 7:28 AM, Christofer Bogaso wrote:
Thanks Bert for your reply. I am trying to understand/visualize the Sample Chi-Squared Statistic's Null distribution. Therefore I need all possible Contingency tables under Independence case. What could be better way to visualize that?
In your quest for enlightenment, consider looking at the example in: ?r2dtable
David. > > Thanks and regards, > > On 01 December 2012 20:03:00, Bert Gunter wrote: >> Christopher: >> >> Don't do this! >> >> If I understand you correctly, you want FIsher's exact test. This is >> already available in R, using far smarter algorithms then you >> would. See: >> >> ?fisher.test >> >> -- Bert >> >> On Sat, Dec 1, 2012 at 5:48 AM, Christofer Bogaso >> <bogaso.christofer at gmail.com <mailto:bogaso.christofer at gmail.com>> >> wrote: >> >> Thanks John for your reply. However still not clear how I should >> proceed. >> >> My goal is to generate all possible contingency tables. Basically >> I want to see the distribution of Chi-squared Statistic under >> independence (NULL). >> >> So I was thinking if I can generate all possible permutation of >> integer numbers having sum equal to (8 + 10 + 12 + 6) = 36. Is >> there any R function to do that? >> >> Thanks and regards, >> >> >> On 01-12-2012 18:39, John Kane wrote: >> >> Are you basically asking for all possible permutations of the >> table? If so see ?permn in the combinat package. >> >> John Kane >> Kingston ON Canada >> >> >> -----Original Message----- >> From: bogaso.christofer at gmail.com >> <mailto:bogaso.christofer at gmail.com> >> Sent: Sat, 01 Dec 2012 18:10:15 +0545 >> To: r-help at r-project.org <mailto:r-help at r-project.org> >> Subject: [R] 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 scenario (one of them would obviously be the >> given table >> as, we could not reject the independence), and for each >> such table I >> want to calculate the Ch-sq statistic. >> >> Can somebody help me how to generate all such tables? >> >> Thanks and regards, >> >> David Winsemius, MD Alameda, CA, USA