diff --git a/Math/Statistic/Forecast/Regression/LevelLevelRegression.php b/Math/Statistic/Forecast/Regression/LevelLevelRegression.php
index 64ecbfeb8..1d6a29bd4 100644
--- a/Math/Statistic/Forecast/Regression/LevelLevelRegression.php
+++ b/Math/Statistic/Forecast/Regression/LevelLevelRegression.php
@@ -26,11 +26,17 @@ namespace phpOMS\Math\Statistic\Forecast\Regression;
  */
 class LevelLevelRegression extends RegressionAbstract
 {
+	/**
+     * {@inheritdoc}
+     */
     public static function getSlope(float $b1, float $y, float $x) : float
     {
         return $b1;
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getElasticity(float $b1, float $y, float $x): float
     {
         return $b1 * $y / $x;
diff --git a/Math/Statistic/Forecast/Regression/LevelLogRegression.php b/Math/Statistic/Forecast/Regression/LevelLogRegression.php
index cbc7fbccb..6d503b4e8 100644
--- a/Math/Statistic/Forecast/Regression/LevelLogRegression.php
+++ b/Math/Statistic/Forecast/Regression/LevelLogRegression.php
@@ -44,11 +44,17 @@ class LevelLogRegression extends RegressionAbstract
         return parent::getRegression($x, $y);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getSlope(float $b1, float $y, float $x) : float
     {
         return $b1 / $x;
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getElasticity(float $b1, float $y, float $x): float
     {
         return $b1 / $x;
diff --git a/Math/Statistic/Forecast/Regression/LogLevelRegression.php b/Math/Statistic/Forecast/Regression/LogLevelRegression.php
index 2fd5ab87d..bad6be188 100644
--- a/Math/Statistic/Forecast/Regression/LogLevelRegression.php
+++ b/Math/Statistic/Forecast/Regression/LogLevelRegression.php
@@ -44,11 +44,17 @@ class LogLevelRegression extends RegressionAbstract
         return parent::getRegression($x, $y);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getSlope(float $b1, float $y, float $x) : float
     {
         return $b1 * $y;
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getElasticity(float $b1, float $y, float $x): float
     {
         return $b1 * $x;
diff --git a/Math/Statistic/Forecast/Regression/LogLogRegression.php b/Math/Statistic/Forecast/Regression/LogLogRegression.php
index 8f8bfa1e7..af28cc263 100644
--- a/Math/Statistic/Forecast/Regression/LogLogRegression.php
+++ b/Math/Statistic/Forecast/Regression/LogLogRegression.php
@@ -45,11 +45,17 @@ class LogLogRegression extends RegressionAbstract
         return parent::getRegression($x, $y);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getSlope(float $b1, float $y, float $x) : float
     {
         return $b1 * $y / $x;
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getElasticity(float $b1, float $y, float $x): float
     {
         return $b1;
diff --git a/Math/Statistic/Forecast/Regression/MultipleLinearRegression.php b/Math/Statistic/Forecast/Regression/MultipleLinearRegression.php
index d68611f1b..71a8cb637 100644
--- a/Math/Statistic/Forecast/Regression/MultipleLinearRegression.php
+++ b/Math/Statistic/Forecast/Regression/MultipleLinearRegression.php
@@ -33,10 +33,16 @@ class MultipleLinearRegression
         return $XT->mult($X)->inverse()->mult($XT)->mult($Y)->getMatrix();
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getVariance() : float
     {
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public static function getPredictionInterval() : array
     {
     }