splom tutorial comment.

Author: daslu

src/data_visualization/splom_tutorial.clj

@@ -975,7 +975,11 @@ domains
 ;;
 ;; Notice the symmetry: the upper and lower triangles are mirror images of each other
 ;; (x vs y in one panel corresponds to y vs x in the reflected panel).
-;; Some SPLOM designs only show one triangle to avoid redundancy.
+;; The regression lines, though, are not symmetric. The two axes have different roles
+;; in the definition of regression, that uses x as a predictor and minimizes the 
+;; prediction error for y.
+;; Some SPLOM designs only show one triangle to avoid redundancy. Others use each triangle
+;; for a different data visualization.
 
 
 ;; ## Reflection: What We've Built