Merge branch 'master' into jonathan

* master:
  Fixed formula term order bug.
  Fix small typo with factor name.

doc/ancova.rst

@@ -92,9 +92,9 @@ would yield
    {1: {}, X: {('E',): [('E', 'indicator')], ('P',): [('P', 'contrast')]}}
    {1: {}, X: {('E',): [('E', 'contrast')], ('P',): [('P', 'indicator')]}}
 
-In the first formula, *M* appears as a contrast while *E* appears
+In the first formula, *P* appears as a contrast while *E* appears
 as an indicator. In the second formula, *E* appears as a contrast
-and *M* as an indicator.
+and *P* as an indicator.
 
 Two-way interactions
 ~~~~~~~~~~~~~~~~~~~~

formula/ancova.py

@@ -311,11 +311,10 @@ def formula(self):
         >>>
 
         """
-
-        f = self.formulae[0]
-        for ff in self.formulae[1:]:
-            f = f + ff
-        return f.delete_terms(Formula([0]))
+        terms = []
+        for ff in self.formulae:
+            terms += list(ff.terms)
+        return Formula(terms)
 
     # Methods