diff --git a/app/models/item.py b/app/models/item.py
index dba3b3e..8869a6d 100644
--- a/app/models/item.py
+++ b/app/models/item.py
@@ -13,7 +13,7 @@ class Item(BaseModel):
     workflow_state: Optional[str] = None
     attributes: List[Attribute] = None
     b_param: float = 0.00
-    response: Optional[str] = None
+    response: Optional[int] = None
 
     def iif(self, solver_run, theta):
         return ItemInformationFunction(solver_run.irt_model).calculate(b_param=self.b_param, theta=theta)