CTABLES comments

[pspp] / src / language / stats / ctables.c

diff --git a/src/language/stats/ctables.c b/src/language/stats/ctables.c
index 5eb4bb4a3d1394c9028b1bfadf187b8556db737e..fe46f10c9254cb8e556ff045e24792503af5771c 100644 (file)
--- 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: