From: John Darrington <john@darrington.wattle.id.au>
Date: Sun, 2 Feb 2020 10:51:42 +0000 (+0100)
Subject: Fix bug #57722.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=513a8d92d1679e51701c579d66a912b531e4ec7d;p=pspp

Fix bug #57722.

The McNemar binomial probability should use the minimum of the two dissimilar
group counts.
---

diff --git a/src/language/stats/mcnemar.c b/src/language/stats/mcnemar.c
index ef84b77a4e..7ee52f4313 100644
--- a/src/language/stats/mcnemar.c
+++ b/src/language/stats/mcnemar.c
@@ -235,7 +235,9 @@ output_statistics_table (const struct two_sample_test *t2s,
         pairs->root, pivot_value_new_user_text_nocopy (make_pair_name (vp)));
 
       double n = mc[i].n00 + mc[i].n01 + mc[i].n10 + mc[i].n11;
-      double sig = gsl_cdf_binomial_P (mc[i].n01, 0.5, mc[i].n01 + mc[i].n10);
+      double sig = gsl_cdf_binomial_P ((mc[i].n01 > mc[i].n10) ? mc[i].n10: mc[i].n01,
+				       0.5, mc[i].n01 + mc[i].n10);
+
       double point = gsl_ran_binomial_pdf (mc[i].n01, 0.5,
                                            mc[i].n01 + mc[i].n10);
       double entries[] = { n, 2.0 * sig, sig, point };
diff --git a/tests/language/stats/npar.at b/tests/language/stats/npar.at
index 377832cfe9..820b28ad0f 100644
--- a/tests/language/stats/npar.at
+++ b/tests/language/stats/npar.at
@@ -1261,6 +1261,50 @@ v1 & junk,20,.453,.227,.164
 AT_CLEANUP
 
 
+AT_SETUP([NPAR TESTS McNemar Symetricity])
+
+AT_DATA([mcnemar.sps], [dnl
+data list notable list /var1 var2 w (F2.0).
+begin data
+0 0 9
+0 1 8
+1 0 1
+1 1 5
+end data.
+
+weight by w.
+
+NPAR TEST
+	/MCNEMAR var1 WITH  var2 (PAIRED).
+
+NPAR TEST
+	/MCNEMAR var2 WITH  var1 (PAIRED).
+])
+
+AT_CHECK([pspp -O format=csv mcnemar.sps], [0], [dnl
+Table: var1 & var2
+,var2,
+var1,0,1
+0,9,8
+1,1,5
+
+Table: Test Statistics
+,N,Exact Sig. (2-tailed),Exact Sig. (1-tailed),Point Probability
+var1 & var2,23,.039,.020,.02
+
+Table: var2 & var1
+,var1,
+var2,0,1
+0,9,1
+1,8,5
+
+Table: Test Statistics
+,N,Exact Sig. (2-tailed),Exact Sig. (1-tailed),Point Probability
+var2 & var1,23,.039,.020,.02
+])
+
+AT_CLEANUP
+
 AT_SETUP([NPAR TESTS Kolmogorov-Smirnov Uniform parameters given])
 
 AT_DATA([ks-uniform.sps], [dnl