hi, guys !

as you stated in yur first post...
... COUNTIF has trouble with *text* true/false ...

and, yes...
... COUNTIF is getting "confused" in the first example! ...

IF you change your (text) false into falso (spanish or whatever other language)
you will get the "correct" count of "non-uniques" (within countif function)

hth,
hector.

__ OP __
The test C1:C5<"" counts the FALSE as a value, whereas the COUNTIF ignores it.

No, COUNTIF is counting it. That's the problem.
Within COUNTIF:
false = FALSE and FALSE&"" = FALSE

But
false < false and FALSE&"" < false

So each element of the criteria array is being matched to the logical FALSE in the range array and being counted.

My actual data didn't contain any logicals but it did contain text true/false. I used this:

=SUMPRODUCT((A2:A3992<"")/COUNTIF(A2:A3992,A2:A3992&"*"))

The samples I posted were the results of me tinkering.

Another thing to consider is if the data did contain either true/TRUE and/or false/FALSE should they be considered equal or not?

Also note that the above formula will not work on numbers
--
Biff
Microsoft Excel MVP