addressed issue #2231

Author: jirhiker

pychron/graph/regression_graph.py

@@ -592,7 +592,7 @@ def _poly_regress(self, scatter, r, fit):
             return
 
         r.set_truncate(scatter.truncate)
-        r.determine_fit()
+        r.determine_fit(fit)
         r.calculate()
 
         self._set_excluded(scatter, r)