Need some help in a formula to get the difference between the first and last record values in a group. For example, given the data:
MemberID   AssessDate   AssessValue
1          1/1/2000     10
1          1/15/2000    13
1          1/30/2000    15
2          1/6/2000     60
2          2/15/2000    30
2          2/16/2000    75
2          3/18/2000    80
3          1/2/20000    40
3          2/10/2000    42

I would want to see a grouping by the memberID, and within the details of the group I want to see all the dates and scores, but on the group footer I would want to see the difference from the first AssessValue and the last AssessValue. So, for member #1, I would see 5, for member 2, I would see 20, for member 3 it would be 2.

The AssessDates will vary for all MemberID's and the number of records per group/member will be different, with some having 2 and others having 10+.

Any help is greatly appreciated.