From c1b1583b96cc05a2bf9f3f6d01bbfa063fafb253 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sun, 14 Aug 2022 21:04:52 -0700
Subject: [PATCH] Docment how CLABELS can affect calculations.

---
 doc/automake.mk                |  2 ++
 doc/pspp-figures/ctables23.sps |  2 ++
 doc/pspp-figures/ctables24.sps |  4 ++++
 doc/statistics.texi            | 27 +++++++++++++++++++++++++++
 4 files changed, 35 insertions(+)
 create mode 100644 doc/pspp-figures/ctables23.sps
 create mode 100644 doc/pspp-figures/ctables24.sps

diff --git a/doc/automake.mk b/doc/automake.mk
index e99b82c6ee..daf47cf975 100644
--- a/doc/automake.mk
+++ b/doc/automake.mk
@@ -139,6 +139,8 @@ FIGURE_SYNTAX = \
  doc/pspp-figures/ctables20.sps \
  doc/pspp-figures/ctables21.sps \
  doc/pspp-figures/ctables22.sps \
+ doc/pspp-figures/ctables23.sps \
+ doc/pspp-figures/ctables24.sps \
  doc/pspp-figures/crosstabs.sps \
  doc/pspp-figures/descriptives.sps \
  doc/pspp-figures/flip.sps \
diff --git a/doc/pspp-figures/ctables23.sps b/doc/pspp-figures/ctables23.sps
new file mode 100644
index 0000000000..df37390d46
--- /dev/null
+++ b/doc/pspp-figures/ctables23.sps
@@ -0,0 +1,2 @@
+GET FILE='nhtsa.sav'.
+CTABLES /TABLE AgeGroup BY qns3a [ROWPCT, COLPCT].
diff --git a/doc/pspp-figures/ctables24.sps b/doc/pspp-figures/ctables24.sps
new file mode 100644
index 0000000000..7a12c08037
--- /dev/null
+++ b/doc/pspp-figures/ctables24.sps
@@ -0,0 +1,4 @@
+GET FILE='nhtsa.sav'.
+CTABLES
+    /TABLE AgeGroup BY qns3a [ROWPCT, COLPCT]
+    /CLABELS COLLABELS=OPPOSITE.
diff --git a/doc/statistics.texi b/doc/statistics.texi
index 7ac4191bb8..2e133dd651 100644
--- a/doc/statistics.texi
+++ b/doc/statistics.texi
@@ -1500,6 +1500,33 @@ column variable category labels, respectively, to the layer axis.
 Only one axis's labels may be moved, whether to the opposite axis or
 to the layer axis.
 
+@subsubheading Effect on Summary Statistics
+
+@code{CLABELS} primarily affects the appearance of tables, not the
+data displayed in them.  However, @code{CTABLES} can affect the values
+displayed for statistics that summarize areas of a table, since it can
+change the definitions of these areas.
+
+For example, consider the following syntax and output:
+
+@example
+CTABLES /TABLE AgeGroup BY qns3a [ROWPCT, COLPCT].
+@end example
+@psppoutput {ctables23}
+
+@noindent
+Using @code{COLLABELS=OPPOSITE} changes the definitions of rows and
+columns, so that column percentages display what were previously row
+percentages and the new row percentages become meaningless (because
+there is only one cell per row):
+
+@example
+CTABLES
+    /TABLE AgeGroup BY qns3a [ROWPCT, COLPCT]
+    /CLABELS COLLABELS=OPPOSITE.
+@end example
+@psppoutput {ctables24}
+
 @node CTABLES Per-Variable Category Options
 @subsection Per-Variable Category Options
 
-- 
2.30.2