Harlan,

Will your formula return a "0" or an error if there are no values for a particular 1 week period? Is it possible to have it return a numeric value only if there are more than some number of records, say 24?

Edit: Actually, instead of dividing by 168, can it divide by the number of numeric values that exist within a particular range? I have a few gaps in my data due to failed temperature loggers.

Thanks again