=SUM(--(FREQUENCY(IF(B1:B10="X",MATCH(A1:A10,A1:A10,0)),R OW(INDIRECT("1:"&RO
WS(A1:A10))))0))

which is an array formula, it should be committed with Ctrl-Shift-Enter, not
just Enter.

--
HTH

Bob Phillips

(remove xxx from email address if mailing direct)

"Kent (thanks)" wrote in message
...
You are correct, there are 4 unique values in column A, but I only want
them
to be counted if there is a corresponding (X) in column B. Thus, based on
my
example, "3" should not be counted as a unique value as there is no
corresponding "X" in column B.

"JethroUK©" wrote:

There are 4 unique values in your example of column A:

you can count them with array formula:

=SUM(COUNTIF(A1:A10,A1:A10)/COUNTIF(A1:A10,A1:A10)^2)

but i think you need to describe exactly what you mean by "..based on
set
criteria in Column B.."



"Kent (thanks)" wrote in message
...
I have a spreadsheet where I am trying to count the number of unique
values
in Column A, based on set criteria in Column B. I have searched all
over
the
internet and the most popular solution seems to be the formula below.
For
examples purposes assume the following:
A B
1 X
2 Y
2 X
3 Y
3 Y
4 X
4 X
4 X

I use the following array formula to count the number of unique
numbers in
column A, based on (X) in column B.

=SUM(1/COUNTIF(A1:A8,A1:A8)*(B1:B8="x"))

I would expect the result to be 3, but instead I get 2.5

Any suggestions on how to correct my formula? My actual spreadsheet
includes both numeric and alpha fields that need to be counted, but no
blank
spaces.

Thanks in advance for your assistance,