Average of all records...?

[merlyn383]

I've created a rather simple grade database that computes each individual student's average and I would like to compare those averages and to automate some responses using them. For example: I would like an average of a particular field over all records. I have tried using summaries but I have found them to be useless because they only summarize the records that are in the current found set. Is there any way to accomplish what I'm trying to do?

I can clarify this further if anyone needs it.

[Reed]

You could use a calculation field that is the average of all records. use the cartesian product (x) relational operator to create a self join. the calc field would be average(join_table::field)

[ESpringer]

Merlyn,

The way that I have used to get what you're talking about is to create various self-join relations. In particular, you can add another table occurrence of your assignment submissions table, and create a match between the Assignment field in the main table and its equivalent in the other table occurrence (which I'd call AssgnSJ or something like that). So, now all things labeled "Quiz 1" (or whatever) have a relation to each other. You can then do calculations on this relationship, such as Count(AssignSJ::Score) and Average(AssignSJ::Score). When you're looking at a record for a Quiz 1 score, you'll see the average of Quiz 1 work, across students. When you're looking at a record for Final Project score, you'll see the average of Final Project scores. If you store grades for multiple classes, you can further constrain the relationship so that it matches on the assignment name AND on the Class field...

In my grading databases, I even multiple portals on the assignment submission layout: one displays and takes me to any other work by that student, and another displays and easily takes me to other work on this assignment.

Is that in the ballpark?

[merlyn383]

Thanks guys. Both of you helped a lot.