Druid ThetaSketch Related Query

Hi,

I have query related to behavior of druid thetaSketch .

I have total unique records in file = 594081 . When i ingest file to druid with thetaSketch default size=16384 , i got unique user count = 589149 . so i got bug percent near around = 0.8% .

Next time i increase thetaSketch size=65536 (4 time to default) , i got unique user count = 585288 (during query time i used size=65536) which is less then earlier got count (589149 with default thetaSketch Count) .

So here is my query:-- As druid doc http://druid.io/docs/latest/development/extensions-core/datasketches-aggregators , if need higher accuracy , i have to increase high size (power of 2) . That i did but i am not getting high accuracy instead bug percent increase. So want to know is it possible??