You learn something new every day! I've probably done a 100 or more compression tests and have never done this! I know, I know... I only know what I've been taught and I guess dad taught me wrong!
Time to eat some humble pie!
Now I'm real curious! What is really amazing, is that I've never encountered this before.
http://www.geocities.com/dsmgrrrl/FAQs/compression.htm