diff --git a/variable_generators/generators.py b/variable_generators/generators.py
index 0e02f05..a343573 100644
--- a/variable_generators/generators.py
+++ b/variable_generators/generators.py
@@ -76,13 +76,13 @@ def func():
     return func
 
 
-def make_size_var(agent, geog, geog_id):
+def make_size_var(agent, geog, geog_id, cache_scope='step'):
     """
     Generator function for size variables. Registers with orca.
     """
     var_name = 'total_' + agent
 
-    @orca.column(geog, var_name, cache=True, cache_scope='iteration')
+    @orca.column(geog, var_name, cache=True, cache_scope=cache_scope)
     def func():
         agents = orca.get_table(agent)
         print('Calculating number of {} for {}'.format(agent, geog))