X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Flanguage%2Fstats%2Fctables.c;h=fe46f10c9254cb8e556ff045e24792503af5771c;hb=cde27d1dbffdaeab2b4b8c03c0103d7a2db6b16b;hp=5eb4bb4a3d1394c9028b1bfadf187b8556db737e;hpb=3feb6814ce651b7f284b12ecd998a2c09971b479;p=pspp

diff --git a/src/language/stats/ctables.c b/src/language/stats/ctables.c
index 5eb4bb4a3d..fe46f10c92 100644
--- a/src/language/stats/ctables.c
+++ b/src/language/stats/ctables.c
@@ -2231,6 +2231,24 @@ ctables_summary_add (union ctables_summary *s,
                      const struct variable *var, const union value *value,
                      double d_weight, double e_weight)
 {
+  /* To determine whether a case is included in a given table for a particular
+     kind of summary, consider the following charts for each variable in the
+     table.  Only if "yes" appears for every variable for the summary is the
+     case counted.
+
+     Categorical variables:                    VALIDN   COUNT   TOTALN
+       Valid values in included categories       yes     yes      yes
+       Missing values in included categories     ---     yes      yes
+       Missing values in excluded categories     ---     ---      yes
+       Valid values in excluded categories       ---     ---      ---
+
+     Scale variables:                          VALIDN   COUNT   TOTALN
+       Valid value                               yes     yes      yes
+       Missing value                             ---     yes      yes
+
+     Missing values include both user- and system-missing.  (The system-missing
+     value is always in an excluded category.)
+  */
   switch (ss->function)
     {
     case CTSF_COUNT: