[phenixbb] reflection outliers detection in phenix.refine

[guanrj at foxmail.com]

Hi All

I have a question regarding reflection outliers detection in phenix.refine:
in my input reflection file, there are 24432 reflections, but only 22769 of them 
were used in refinement. I checked the log file and saw 1663 outliers. 

(below if from the log)
basic_wilson_outliers    = 14
extreme_wilson_outliers  = 18
beamstop_shadow_outliers = 0
model_based_outliers     = 1657
total                    = 1663

What is the  "model_based_outliers"?  What causes so many reflections rejected
and not used in the refinement?     

Thanks

Rongjin