diff --git a/backend/src/main/java/ervu_business_metrics/model/chart/ColumnAggregationDataSet.java b/backend/src/main/java/ervu_business_metrics/model/chart/ColumnAggregationDataSet.java
index 67224ab..b577425 100644
--- a/backend/src/main/java/ervu_business_metrics/model/chart/ColumnAggregationDataSet.java
+++ b/backend/src/main/java/ervu_business_metrics/model/chart/ColumnAggregationDataSet.java
@@ -30,7 +30,7 @@ public class ColumnAggregationDataSet {
 
   public String yAxesId;
 
-  public Float tension;
+  public String tension;
 
   public Integer drawOrder;
 
diff --git a/resources/src/main/resources/business-model/ervu-business-metrics/logging.page b/resources/src/main/resources/business-model/ervu-business-metrics/logging.page
index 6d96cb6..df5deca 100644
--- a/resources/src/main/resources/business-model/ervu-business-metrics/logging.page
+++ b/resources/src/main/resources/business-model/ervu-business-metrics/logging.page
@@ -21819,12 +21819,6 @@
                 <implRef/>
             </value>
         </entry>
-        <entry>
-            <key>tension</key>
-            <value>
-                <simple>null</simple>
-            </value>
-        </entry>
     </complex>
 </value>
                             </item>
@@ -25924,12 +25918,6 @@
                 <implRef/>
             </value>
         </entry>
-        <entry>
-            <key>tension</key>
-            <value>
-                <simple>null</simple>
-            </value>
-        </entry>
     </complex>
 </value>
                             </item>
@@ -27196,12 +27184,6 @@
                 <implRef/>
             </value>
         </entry>
-        <entry>
-            <key>tension</key>
-            <value>
-                <simple>null</simple>
-            </value>
-        </entry>
     </complex>
 </value>
                             </item>
@@ -28873,12 +28855,6 @@
                 <implRef/>
             </value>
         </entry>
-        <entry>
-            <key>tension</key>
-            <value>
-                <simple>null</simple>
-            </value>
-        </entry>
     </complex>
 </value>
                             </item>