I wonder whether the problem is your use of the date -- not the format.
Excel stores dates as an integer, starting with 1/1/1900. So April 14, 2008
is stored as 39552. (The modulus to the right of the decimal point is
essentially the % of the day elapsed...)

Perhaps if you set your first day as a 'day 0', with subsequent days
numbered accordingly?

HTH

"OBR" wrote:

I had Excel develop a 6th order polynomial regression with Dates (M/D/Y) as
the independent variable (x) and Hydraulic Flow as the dependant variable
(y). Unfortunately, when I try to use the equation to generate Hydraulic Flow
values the equation outputs extremely large numbers that make no sense.
I imagine that the problem has to do with the Date format. Does any one have
a solution for this issue?
Regards,
OBR