diff --git a/components/number.inc b/components/number.inc
index 8134b49..46bedd8 100644
--- a/components/number.inc
+++ b/components/number.inc
@@ -438,6 +438,10 @@ function _webform_analysis_number($component, $sids = array(), $single = FALSE)
       $stddev = sqrt($stddev);
     }
 
+    if(empty($stddev)){
+      return $rows;
+    }
+
     // Build normal distribution table rows.
     $count = array();
     $percent = array();