diff --git a/approach/images/cohort-timeline.drawio b/approach/images/cohort-timeline.drawio
new file mode 100644
index 0000000..eaed7f7
--- /dev/null
+++ b/approach/images/cohort-timeline.drawio
@@ -0,0 +1,10 @@
+<mxfile host="app.diagrams.net" modified="2023-09-05T16:40:36.711Z" agent="Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36" version="21.7.2" etag="x0pZOzdamFhzNpqaHxWi" type="github">
+  <diagram name="Page-1" id="ZA5AEV3mI3UHnZCHu-64">
+    <mxGraphModel>
+      <root>
+        <mxCell id="0" />
+        <mxCell id="1" parent="0" />
+      </root>
+    </mxGraphModel>
+  </diagram>
+</mxfile>