Here's another way...

=AVERAGE(IF(B2:B6<"",B2:B6-A2:A6))

....confirmed with CONTROL+SHIFT+ENTER. Note that this formula allows
formula blanks ("").

--
Domenic
http://www.xl-central.com

In article ,
mckzach wrote:

Greetings all,

I am working with two columns (ranges) of dates, although there are many
blank rows interspersed in both ranges. I simply need to calculate the
overall average days elapsed between the two columns. In other words, I'm
looking for a single result here; Col. B (End date) - Col. A (Start date) for
as many rows of dates that exist.

COL A (Start) COL B (End)
01/05/09 02/20/09
03/12/09 03/09/09

01/15/09 01/30/09
02/19/09 02/22/09

The array formula I'm using (below) works, but is factoring in the blank
cells and is giving me a lower inaccurate result.

{=AVERAGE((B$2:B$100)-(A$2:A$100))}

Any help at all would be appreciated.