Actual and Estimated rows differ greatly

The full Actual plan is here. Prior to executing the plan (because I'm debugging a poorly functioning plan) I have this block of variable assignments: DECLARE @Days INT = 180 DECLARE @DateRangeFrom DateTime = DATEADD(d, -@Days, getDate()) DECLARE @DateRangeTo DateTime = getDate() DECLARE @FacilityID INT = 1010 DECLARE @Answer0 INT = 1879 DECLARE @Answer1 INT = 1949 DECLARE @Answer1SetID INT = 1607 DECLARE @Answer2 INT = 1907 DECLARE @Answer2SetID INT = 1593 My first problem is with the lookup I'm performing on the IRItemAnswer_Info table (Node ID 19). It's spilling to Tempdb which already starts the query off on the wrong foot. It's referencing the IRItemAnswerInfo_DGItemID_AnswerSourceID index, which is the correct index, as I'm matching on DGItemID and AnswerSourceID, and getting back IncidentID. The index is created as CREATE NONCLUSTERED INDEX IRItemAnswerInfo_DGItemID_AnswerSourceID ON dbo.IRItemAnswer_Info (DGItemID, AnswerSourceID) INCLUDE([IncidentID], [AnswerBoolean]) However, the Estimated Rows for the query is 53,459 and the Actual Rows is 969,812. I just finished forcing new statistics via UPDATE STATISTICS IRItemAnswer_Info IRItemAnswerInfo_DGItemID_AnswerSourceID WITH FULLSCAN and it made no difference. DBCC SHOW_STATISTICS ('IRItemAnswer_Info', 'DGItemID') for DGItemID=1949 has EQ_ROWS as 1,063,536 and DBCC SHOW_STATISTICS ('IRItemAnswer_Info', 'AnswerSourceID') for AnswerSourceID=1607 has EQ_ROWS as 970,079 The database is running Compatibility level 140 (SQL Server 2017). We would run 2019, but there are issues we need to correct in the stored procedures before we can do that. What should be the next thing I look at? --- I chose the worst performing output, which is the most common values. IRItemAnswer_Info is a table containing user-defined answers to associate to an event, where DGItemID=1949 is one of the most common questions (almost every event has one), and where AnswerSourceID=1607 is the most common answer. Given that there is a strong correlation between them, how should I reorder the query? As it is a point of a little bit of confusion, there are two INNER JOINs to the same table, IRItemAnswer_Info. One is the answer I'm looking for (as identified by the question iria.DGItemID=1879 and its output iria.AnswerSourceID links to irai.AltLabel), and the second one is a limiting factor. I only want records where the question iiai1.DGItemID=1949 has as its answer iiai1.AnswerSourceID=1607. I have explicitly removed the plan from the cache (using DBCC FREEPROCCACHE) and re-run it, with no change in the result - the Hash Match is still spilling.