diff --git a/src/elexsolver/TransitionSolver.py b/src/elexsolver/TransitionSolver.py
index 3eee22fd..0c98b597 100644
--- a/src/elexsolver/TransitionSolver.py
+++ b/src/elexsolver/TransitionSolver.py
@@ -11,15 +11,13 @@
 LOG = logging.getLogger(__name__)
 
 
-def mean_absolute_error(Y_expected: np.ndarray, Y_pred: np.ndarray):
+def mean_absolute_error(Y_expected: np.ndarray, Y_pred: np.ndarray, weights: np.ndarray | None = None):
     if isinstance(Y_expected, list):
         Y_expected = np.array(Y_expected)
     if isinstance(Y_pred, list):
         Y_pred = np.array(Y_pred)
 
-    absolute_errors = np.abs(Y_pred - Y_expected)
-    error_sum = np.sum(absolute_errors)
-    return error_sum / len(absolute_errors)
+    return np.average(np.abs(Y_expected - Y_pred), weights=weights)
 
 
 def weighted_absolute_percentage_error(Y_expected: np.ndarray, Y_pred: np.ndarray):