Well, I did say "about 37% if you consider .gz as baseline", but I agree that it could have been worded better. The problem is what you are measuring. If you

Well, I did say "about 37% if you consider .gz as baseline", but I agree that it could have been worded better. The problem is what you are measuring. If you have to compress a 100MB file, and algorithm A/B/C/D compress it to 10/9/1/0.9MB, respectively, then we can argue that "B is 10% better than A" (because the file is 10% smaller) and also "D is 10% better than C" (same). However, moving from A to B saves us 1MB for this file. Moving from C to D only saves us 0.1MB. So depending on how you look at it, you could also argue that the difference between C and D is really only 0.1% (of the original file size). It may not be what you want (for a particular situation), but it's not wrong.