How do I take and average of grouped data?

[Guest]

How do I get averages of grouped data in an access report, as opposed to one
overall average? I have a table of ~45,000 entries. Each entry contains
info regarding a single stocked fish. I have created a report that groups
only the following stocking data:

Year River River Mile Average Length
1996 CO 312
309
GR 96
1997 CO 303
312
GR etc.
etc.
1998
etc.

When I enter =Avg([Length]) in the length column of the report, I get an
average of all of the stocked fish. What I need, for example, is an average
length of the fish stocked in 1996 in the CO river at river mile 312, an
average length of the fish stocked in 1996 in the CO river at river mile 309,
etc. I am not extremely familiar with Access so if someone could help me
with this I would really appreciate it!

 

[Duane Hookom]

Apparently your report is grouped by Year and River? If so, you should place
your =Avg([Length]) in the appropriate group header or footer.