Description of CHNG as-of estimation problems

rumackaaron · rumackaaron · commit e9383f5d52b2 · 2021-10-04T16:49:16.000-04:00
diff --git a/docs/api/covidcast-signals/chng.md b/docs/api/covidcast-signals/chng.md
@@ -185,6 +185,10 @@ Note that due to local differences in health record-keeping practices, estimates
 are not always comparable across locations. We are currently working on
 adjustments to correct this spatial bias.
 
+Indicator values for as-of dates before 2021-02-21 are merely estimates, as
+these indicators were not yet available in real time. Backfill behavior of
+these estimates is erratic and not indicative of current backfill behavior.
+
 ## Qualifying Conditions
 
 We receive data on the following six categories of counts:
