On Oct 5, 2:13 pm, jpm wrote:
Does anyone know an easy way to calculate Nash-Sutcliffe
efficiency in EXCEL?

I know nothing about Nash-Sutcliffe. But based on the Wikipedia entry
[1], I think the following might work (untested):

=1 - sumproduct((A1:A12 - B1:B12)^2) / sumproduct((A1:A12 - C1)^2)

where C1 is:

=average(A1:A12)

and A1:A12 contains the observed discharges Qo, and B1:B12 contains
the modeled discharges Qm.

HTH.


Endnotes:

[1] http://en.wikipedia.org/wiki/Nash-Su...cy_coefficient