"Bruce Norris" wrote...
"Harlan Grove" wrote in message
....
=SUMPRODUCT((Rng<"")*(COUNTIF(Rng,Rng)1)/(COUNTIF(Rng,Rng)+(Rng="")))
....
. . . Can you see any advantage to yours over the one Max offered?

Which is (using same range name)

=SUM(IF(LEN(Rng)0,1/COUNTIF(Rng,Rng)))-SUM(--(COUNTIF(Rng,Rng)=1))

Max's might be more recalc efficient, but array formulas can be perverse at
times. Max's also is shorter, which is usually better. However, I didn't
need one of my numerator tests since blank cells in Rng have count 0, so
make that

=SUMPRODUCT((COUNTIF(Rng,Rng)1)/(COUNTIF(Rng,Rng)+(Rng="")))

which is now shortest.