# Calculating Change Between Two Records Out of Many

Question asked by BG_1 on Jan 24, 2011
Latest reply on Jan 31, 2011 by BG_1

### Title

Calculating Change Between Two Records Out of Many

### Post

Hello everyone,

I have data from students who took a test before taking a class and after.  I am looking for changes in attitude of each particular student (meaning I don't want to calculate the total average change in attitude from pre-test to pro-test). I tried to use a pretty standard survey set-up, using the forums as a guide.

It is set up so that each question has it's own record. Each student has his/her own ID#, and will have records for every questions they filled out times 2 (since they took a pre-test and post-test).  What I need to do is have Filemaker calculate the changes in the 73 questions (from pre-test to post-test).

I don't know how to tell filemaker to do this.  Put in more mathy terms:

If Duplicate Student ID exits, Take the Difference of Q1 in Pre-Test and Q1 in Post-Test = Attitude Change

If Duplicate Student ID exits, Take the Difference of Q2 in Pre-Test and Q2 in Post-Test = Attitude Change

If Duplicate Student ID exits, Take the Difference of Q3 in Pre-Test and Q3 in Post-Test = Attitude Change

....

The fields I am using:  ID (Student ID), QID (Question Number, not result), Answer (Student Response)

What makes it hard to do for me is that I need it to check for multiple things.  1) It must know to find identical ID#s to compare them.  2) When duplicates are found, I need compare submitted answers of between pre-test and post-test.

So, it's basically checking for the same person, then the same question, then it can finally compare the Answer Fields for those 2 particular records.

Sorry for the mess, but it's the best way I can describe it, thanks!