diff --git a/src/assessment/assessment.lisp b/src/assessment/assessment.lisp
index 2b75263..8696ee1 100644
--- a/src/assessment/assessment.lisp
+++ b/src/assessment/assessment.lisp
@@ -133,6 +133,19 @@ ENTRY: Entry from a response."
                                           collect score)))))
     (append average-scores (list :average overall-average))))
 
+
+(defmethod calculator-calc-group-stats ((calc calculator) results)
+  (when (> (length results) 1)
+      (flet ((merge-entry (acc entry)
+               (loop :for (key value) :on entry :by #'cddr
+                     :do (push value (getf acc key)))
+               acc))
+        (let ((merged-values (reduce #'merge-entry
+                                     (mapcar #'cddr results)
+                                     :initial-value '())))
+          (reverse (loop :for (key value) :on merged-values :by #'cddr
+                         :collect (list key (calculate-statistics value))))))))
+
 ;;; Displayer
 
 (defclass displayer ()
diff --git a/src/assessment/sus.lisp b/src/assessment/sus.lisp
index dbbd795..ddc5d3d 100644
--- a/src/assessment/sus.lisp
+++ b/src/assessment/sus.lisp
@@ -25,9 +25,6 @@
                        (cons timestamp
                              (append values (sus-score values))))))
 
-(defmethod calculator-calc-group-stats ((calc sus-calculator) results)
-  (when (> (length results) 1)))
-
 (defclass sus-assessment (assessment) ())
 
 (defmethod initialize-instance :after ((a sus-assessment) &key)
diff --git a/src/assessment/visawi.lisp b/src/assessment/visawi.lisp
index 7a63b4d..8c9f9e3 100644
--- a/src/assessment/visawi.lisp
+++ b/src/assessment/visawi.lisp
@@ -33,19 +33,6 @@ Returns an integer."
                        (cons timestamp (average-score-per-group #'visawi-entry-process
                                                                 (rest response))))))
 
-(defmethod calculator-calc-group-stats ((calc visawi-calculator) results)
-  (if (> (length results) 1)
-      (flet ((merge-entry (acc entry)
-               (loop :for (key value) :on entry :by #'cddr
-                     :do (push value (getf acc key)))
-               acc))
-        (let ((merged-values (reduce #'merge-entry
-                                     (mapcar #'cddr results)
-                                     :initial-value '())))
-          (reverse (loop :for (key value) :on merged-values :by #'cddr
-                         :collect (list key (calculate-statistics value))))))
-      nil))
-
 (defclass visawi-assessment (assessment) ())
 
 (defmethod initialize-instance :after ((a visawi-assessment) &key)