Use significance_of_correlation function in t-test.

[pspp-builds.git] / src / language / stats / t-test.q

diff --git a/src/language/stats/t-test.q b/src/language/stats/t-test.q
index 09a96cfc194930b3cc063c77056622c91455237b..8f23cefd4afa54c8be6cfebe7031128a913e3616 100644 (file)
--- a/src/language/stats/t-test.q
+++ b/src/language/stats/t-test.q
@@ -43,10 +43,12 @@
 #include <libpspp/taint.h>
 #include <math/group-proc.h>
 #include <math/levene.h>
+#include <math/correlation.h>
 #include <output/manager.h>
 #include <output/table.h>
 #include <data/format.h>
 
+#include "minmax.h"
 #include "xalloc.h"
 #include "xmemdup0.h"
 
@@ -506,7 +508,7 @@ ssbox_one_sample_init (struct ssbox *this, struct t_test_proc *proc)
   tab_text (this->t, 1, 0, TAB_CENTER | TAT_TITLE, _("N"));
   tab_text (this->t, 2, 0, TAB_CENTER | TAT_TITLE, _("Mean"));
   tab_text (this->t, 3, 0, TAB_CENTER | TAT_TITLE, _("Std. Deviation"));
-  tab_text (this->t, 4, 0, TAB_CENTER | TAT_TITLE, _("SE. Mean"));
+  tab_text (this->t, 4, 0, TAB_CENTER | TAT_TITLE, _("S.E. Mean"));
 }
 
 /* Initialize the independent samples ssbox */
@@ -526,7 +528,7 @@ ssbox_independent_samples_init (struct ssbox *this, struct t_test_proc *proc)
   tab_text (this->t, 2, 0, TAB_CENTER | TAT_TITLE, _("N"));
   tab_text (this->t, 3, 0, TAB_CENTER | TAT_TITLE, _("Mean"));
   tab_text (this->t, 4, 0, TAB_CENTER | TAT_TITLE, _("Std. Deviation"));
-  tab_text (this->t, 5, 0, TAB_CENTER | TAT_TITLE, _("SE. Mean"));
+  tab_text (this->t, 5, 0, TAB_CENTER | TAT_TITLE, _("S.E. Mean"));
 }
 
 /* Populate the ssbox for independent samples */
@@ -625,7 +627,7 @@ ssbox_paired_init (struct ssbox *this, struct t_test_proc *proc)
   tab_text (this->t, 2, 0, TAB_CENTER | TAT_TITLE, _("Mean"));
   tab_text (this->t, 3, 0, TAB_CENTER | TAT_TITLE, _("N"));
   tab_text (this->t, 4, 0, TAB_CENTER | TAT_TITLE, _("Std. Deviation"));
-  tab_text (this->t, 5, 0, TAB_CENTER | TAT_TITLE, _("SE. Mean"));
+  tab_text (this->t, 5, 0, TAB_CENTER | TAT_TITLE, _("S.E. Mean"));
 }
 
 /* Populate the ssbox for paired values */
@@ -974,8 +976,8 @@ trbox_paired_populate (struct trbox *trb,
       /* Degrees of freedom */
       tab_double (trb->t, 8, i + 3, TAB_RIGHT, df, &proc->weight_format);
 
-      p = gsl_cdf_tdist_P (t, df);
-      q = gsl_cdf_tdist_P (t, df);
+      p = gsl_cdf_tdist_P (t,df);
+      q = gsl_cdf_tdist_Q (t,df);
 
       tab_double (trb->t, 9, i + 3, TAB_RIGHT, 2.0 * (t > 0 ? q : p), NULL);
     }
@@ -1109,10 +1111,6 @@ pscbox (struct t_test_proc *proc)
   for (i = 0; i < proc->n_pairs; i++)
     {
       struct pair *pair = &proc->pairs[i];
-      double p, q;
-      double df = pair->n -2;
-      double correlation_t = (pair->correlation * sqrt (df) /
-                              sqrt (1 - pow2 (pair->correlation)));
 
       /* row headings */
       tab_text_format (table, 0, i + 1, TAB_LEFT | TAT_TITLE,
@@ -1126,10 +1124,8 @@ pscbox (struct t_test_proc *proc)
       tab_double (table, 2, i + 1, TAB_RIGHT, pair->n, &proc->weight_format);
       tab_double (table, 3, i + 1, TAB_RIGHT, pair->correlation, NULL);
 
-      p = gsl_cdf_tdist_P (correlation_t, df);
-      q = gsl_cdf_tdist_Q (correlation_t, df);
-      tab_double (table, 4, i + 1, TAB_RIGHT,
-                 2.0 * (correlation_t > 0 ? q : p), NULL);
+      tab_double (table, 4, i + 1, TAB_RIGHT, 
+                 2.0 * significance_of_correlation (pair->correlation, pair->n), NULL);
     }
 
   tab_submit (table);