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--- analysis:stat:fisherexacttest [2014/12/15 17:56] – created igorkagan
+++ analysis:stat:fisherexacttest [2022/12/29 07:15] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 ====== Fisher's exact test ======
+InStat example:
+{{:analysis:stat:fisherexacttest_instat_example.png?562}}
+Corresponding MATLAB:
+<code matlab>
+%% Fisher's exact test on proportions of two outcomes
+Ns1 = 10; % condition, or status 1 (e.g. control)
+Ns2 = 10; % condition, or status 2 (e.g. stimulation)
+% Let's assign arbitrary outcome 2 ("1") as "success"
+p_suc1 = 0.2; % probability success in status 1
+p_suc2 = 0.9; % probability success in status 2
+y1 = zeros(1,Ns1);
+y2 = ones(1,Ns2);
+x1 = [zeros(1,round(  (1-p_suc1)*Ns1 )) ones( 1, round(p_suc1*Ns1) )];	% status 1 outcome
+x2 = [zeros(1,round(  (1-p_suc2)*Ns2 )) ones( 1, round(p_suc2*Ns2) )];	% status 2 outcome
+p = fexact( [x1 x2]' , [y1 y2]' )
+% approximating by Binomial distribution, 100 times
+% http://www.stat.yale.edu/Courses/1997-98/101/binom.htm
+count_success1 = binornd(Ns1,p_suc1,1,100); % this draws a count of success
+count_success2 = binornd(Ns2,p_suc2,1,100);
+y1 = zeros(1,Ns1);
+y2 = ones(1,Ns2);
+for i = 1:100,
+	x1 = [zeros(1,Ns1-count_success1(i)) ones( 1, count_success1(i) )];	% status 1 outcome
+	x2 = [zeros(1,Ns1-count_success2(i)) ones( 1, count_success2(i) )];	% status 1 outcome
+	p(i) = fexact( [x1 x2]' , [y1 y2]' );
+end
+hist(p<0.05);
+</code>