If I understand you correctly, perhaps this is what you are looking for:

2005 2006
J F M A M J J A S O N D J F M A M
1 4 5 2 7 9 9 3 4 2 1 7 3 2 3 8 5

Under the D: Average(A1:A12)
Under the J: Average(A2:A13)
Under the F: Average(A3:A14)

and so on.

Art
"SamA" wrote:

Art,
What I detailed was the first sequence.

example 1
1/2005 through 12/2006
2/2005 through 1/2006
etc.

thank you for your response.

"Art" wrote:

In your example a rolling 12 month average is the same thing as the average
-- given that you have only listed 12 months. Assuming your values are in
A1-L1, you could put =Average(A1:L1).

Art

"SamA" wrote:

I am trying to create a 12 month rolling average, example follows.

J F M A M J J A S O N D average
item 1 2 3 4 5 6 7 8 9 10 11 12 (rolling average)

thank you