diff --git a/Math/Statistic/Average.php b/Math/Statistic/Average.php
index 0bcd1674d..afd73e357 100644
--- a/Math/Statistic/Average.php
+++ b/Math/Statistic/Average.php
@@ -52,11 +52,11 @@ class Average
      *
      * @since  1.0.0
      */
-    public static function averageChange(array $x, int $h = 1) : float
+    public static function averageDatasetChange(array $x, int $h = 1) : float
     {
         $count = count($x);
 
-        return $x[$count - 1] + $h * ($x[$count - 1] - $x[0]) / ($count - 1);
+        return $h * ($x[$count - 1] - $x[0]) / ($count - 1);
     }
 
     /**
diff --git a/Math/Statistic/MeasureOfDispersion.php b/Math/Statistic/MeasureOfDispersion.php
index 09bc6d104..b74d931ec 100644
--- a/Math/Statistic/MeasureOfDispersion.php
+++ b/Math/Statistic/MeasureOfDispersion.php
@@ -47,7 +47,7 @@ class MeasureOfDispersion
         $end   = end($values);
         $start = reset($values);
 
-        return $start - $end;
+        return $end - $start;
     }
 
     /**