diff --git a/proteobench/modules/dda_quant/datapoint.py b/proteobench/modules/dda_quant/datapoint.py
index 3b8b0f8b..5349aa25 100644
--- a/proteobench/modules/dda_quant/datapoint.py
+++ b/proteobench/modules/dda_quant/datapoint.py
@@ -43,7 +43,8 @@ def calculate_missing_quan_prec(self, df, nr_missing_0):
 
     def calculate_plot_data(self, df):
         # compute mean of epsilon column in df
-        self.weighted_sum = round(df["epsilon"].mean(), ndigits=3)
+        # take abs value of df["epsilon"]
+        self.weighted_sum = round(df["epsilon"].abs().mean(), ndigits=3)
         self.nr_prec = len(df)
 
     def generate_id(self):