diff --git a/dal/db_query/queries.sql b/dal/db_query/queries.sql
index 56e8ebd..6d46608 100644
--- a/dal/db_query/queries.sql
+++ b/dal/db_query/queries.sql
@@ -431,16 +431,24 @@ WITH TimeBucket AS (
          SELECT
              tb.time_interval_start,
              tb.time_interval_end,
-             COUNT(*) AS true_result_count
+             COUNT(DISTINCT session) AS true_result_count
          FROM
-             answer
-                 JOIN TimeBucket tb ON date_trunc('hour', answer.created_at) >= tb.time_interval_start
-                 AND date_trunc('hour', answer.created_at) < tb.time_interval_end
-         WHERE
-             answer.quiz_id = $3
-           AND result = TRUE
-           AND created_at >= $1::timestamp
-           AND created_at <= $2::timestamp
+             (
+                 SELECT
+                     session,
+                     MIN(created_at) AS first_result_time
+                 FROM
+                     answer
+                 WHERE
+                     answer.quiz_id = $3
+                   AND result = TRUE
+                   AND created_at >= $1::timestamp
+                   AND created_at <= $2::timestamp
+                 GROUP BY
+                     session
+             ) AS first_results
+                 JOIN TimeBucket tb ON date_trunc('hour', first_results.first_result_time) >= tb.time_interval_start
+                 AND date_trunc('hour', first_results.first_result_time) < tb.time_interval_end
          GROUP BY
              tb.time_interval_start, tb.time_interval_end
      ),