Please supply a short list of sample dates, and whatever "time periods of
interest" you would like to see..........then perhaps someone can give you a
formula to automate the process.

Vaya con Dios,
Chuck, CABGx3



"LB" wrote:

I am working with water quality data organized by sample date, with samples
taken 2x/month. I need to sum the sampled parameter values for a time period
of interest, with the sample date being the median of that time period. How
do I create the time periods of interest when the samples are not recorded on
the same dates each month?
THanks