MyBarnard 1.0

There are two fundamentally different exact tests for comparing the equality of two binomial probabilities d-deOCt Fisherd-deOaos exact test (Fisher, 1925), and Barnardd-deOaos exact test (Barnard, 1945). Fisherd-deOaos exact test (Fisher, 1925) is the more popular of the two. In fact, Fisher was bitterly critical of Barnardd-deOaos proposal for esoteric reasons that we will not go into here. For 2 doOCo 2 tables, Barnardd-deOaos test is more powerful than Fisherd-deOaos, as Barnard noted in his 1945 paper, much to Fisherd-deOaos chagrin (see C.R. Mehta and P. Senchaudhuri: Conditional versus unconditional exact tests for comparing two binomials. www.cytel.com/papers/twobinomials.pdf). Anyway, perhaps due to its computational difficulty the Barnard's is not widely used. This function is completely vectorized and without for...end loops, and so, the computation is very fast. In FEX there is only one other function that computes the Barnard's exact test by Antonio Trujillo-Ortiz.Using this matrix x=[7 12; 8 3]; switching off the input error checks and display results sections in both functions; the performs are:L=1000; times=zeros(1,L); for I=1:L, tic; mybarnard(x); times(I)=toc; end, median(times)ans = 0.0028L=1000; times=zeros(1,L); for I=1:L, tic; Barnardextest(7,12,8,3); times(I)=toc; end, median(times)ans = 1.2478So my function is about 450 times faster.

Requirements:	No special requirements
Platforms:	Matlab
Keyword:	Antonio,  Computes,  Error,  Input,  Matrix,  Switching,  Trujilloortiz
Users rating:	0/10