If A1 has the year and B1 the period, and we need to go back 3 periods ("4
periods before")
then we want the year given by =A1-(B1<5) which says subtract 1 from A1 if
B1 is less than 5)
and the period given by =B1-3+12*(B1<4) which says subtract 3 from B1 and
add 12 if B1 is less than 4
So since the table has only one entry for any given year/period we may use
SUMPROUDUCT for a two way lookup (or SUMIFS if we have Excel 2007)
I used this and it seems to do what you want:
=SUMPRODUCT(--(Sheet1!$A$2:$A$30=A1-(B1<5)),--(Sheet1!$B$2:$B$30=B1-3+12*(B1<4)),Sheet1!$C$2:$C$30)

Why did you use "Format" for the subject?
best wishes
--
Bernard V Liengme
Microsoft Excel MVP
http://people.stfx.ca/bliengme
remove caps from email


"Tony7659" wrote in message
...
Hi,
I have the table below for 2008/2009. Now, in another sheet in cell A1 I
have the "Year" and in cell B1 I have the "Period". I need a formula to
find
the "Actual" value from the table below for the Period in cell B1. My
issue
is that in my formula I may need let's say the value in cell B1 but 4
prior
periods and as you can see they may fall into the previous year (i.e.
A1=2009, B1=2; I need the actual value 4 prior periods or the value for
period 11, 2008).
Any ideas?
Thanks. Tony.

Year Period Actual
2008 1 $0.0000
2008 2 $0.0000
2008 3 $0.1500
2008 4 $0.2800
2008 5 $0.1500
2008 6 $0.2800
2008 7 $0.3000
2008 8 $0.4800
2008 9 $0.3600
2008 10 $0.0000
2008 11 $0.0000
2008 12 $0.0000
2009 1 $0.4200
2009 2 $0.4800
2009 3 $0.4800
2009 4 $0.5000
2009 5 $0.4800
2009 6 $0.4800
2009 7
2009 8
2009 9
2009 10
2009 11
2009 12