diff --git a/src/bayesvalidrox/post_processing/post_processing.py b/src/bayesvalidrox/post_processing/post_processing.py
index b1ab0e629861e34b4018e1473eddfc619c92a795..51f81eedcf32ca8b7e4b9ce232c1617121babc6d 100644
--- a/src/bayesvalidrox/post_processing/post_processing.py
+++ b/src/bayesvalidrox/post_processing/post_processing.py
@@ -62,7 +62,7 @@ class PostProcessing:
     def PCEMoments(self):
         
         PCEModel = self.PCEModel
-        Model = PCEModel.ModelObj 
+        Model = PCEModel.ModelObj
         
         for Outkey, ValuesDict in PCEModel.coeffs_dict.items():
             
@@ -85,11 +85,11 @@ class PostProcessing:
             else:
                 self.PCEMeans[Outkey] = PCEMean
                 self.PCEStd[Outkey] = np.sqrt(PCEVar)
-        try:  
+        try:
             self.Reference = Model.read_mc_reference()
         except:
             pass
-        
+
     # -------------------------------------------------------------------------
     def plotMoments(self, xlabel='Time [s]', plotType=None, SaveFig=True):
 
@@ -143,7 +143,7 @@ class PostProcessing:
                 ax[1].plot(x, std_data, lw=3, color='k', marker='x',
                            label=metaModel)
 
-            if hasattr(self, 'Reference'):
+            if self.Reference is not None:
                 if barPlot:
                     ax[0].bar(list(map(str, x)), self.Reference['mean'],
                               color='r', width=0.25)
@@ -336,7 +336,7 @@ class PostProcessing:
         
         self.ModelOutputs = self.eval_Model(samples, keyString='valid')
         self.PCEOutputs, self.PCEOutputs_std = metaModel.eval_metamodel(samples=samples)
-        
+
         try:
             key = list(self.ModelOutputs.keys())[1]
         except: