Left out part of the SAMP_PER_MONTH bit... have to multiply by 30.4,
so of course that means (groan) casting that as a double too.

CAST (COUNT(F_SAMPLE_ID) AS DOUBLE PRECISION)
/
CAST((MAX(F_PROCESSDATE) - MIN(F_PROCESSDATE)) AS DOUBLE PRECISION)
* CAST(30.4 AS DOUBLE PRECISION) AS AV_SAMP_PER_MTH

Regards,
Andrew Ferguson
-- Men are from earth. Women are from earth. Deal with it.