diff --git a/notebooks/Baselines for Intervention Prediction - Mechanical Ventilation.ipynb b/notebooks/Baselines for Intervention Prediction - Mechanical Ventilation.ipynb
index b44591c..82ec440 100644
--- a/notebooks/Baselines for Intervention Prediction - Mechanical Ventilation.ipynb	
+++ b/notebooks/Baselines for Intervention Prediction - Mechanical Ventilation.ipynb	
@@ -203,7 +203,6 @@
    "outputs": [],
    "source": [
     "def std_time_since_measurement(x):\n",
-    "    idx = pd.IndexSlice\n",
     "    x = np.where(x==100, 0, x)\n",
     "    means = x.mean()\n",
     "    stds = x.std()\n",