So I assume a +3 would be 15% (or less, if it tapers off, like +5%,+3% whatever) of the base stat, not 5% of the previous amount...if that makes sense.

So a 40 defense stat with 3 starts would be 15% of 40, not 40 +5% =42, 42+5%=44.1, so on..
I admit after doing that example 40 is a bad number...but with higher numbers I think it would make more of an impact.

Just a curiosity, don't really care either way what the method is :P