Statistics Collection Recommendations – Teradata 14.10, 15.0 and 15.10 - comment by carrie

RESPONSE TO SECOND QUESTION:
 
If UDI counts are available, they will always be used instead of random AMP sampling.  So if you see that your histogram for that statistic carries UDI counts then you know that any extrapolation that took place used those counts.   If you don't see any UDI counts in the histogram, then assume that random AMP samples were used for extrapolation purposes.  
 
Thanks, -Carrie