In Dead Island, the character Purna has a Survival skill called Jackpot (just before the bottom) which "increases your chance to find rare items among loot." I was wondering how effective this is, like if there's a 20% chance to find greens, does it bump it up to 21%? Or is there an AwesomeLevel like in Borderlands and it increases the AwesomeLevel of all chests that Purna opens?
I can't test it myself because I can't mod the files, but this thread has two users, Twoframes and Banzure (links to their pertinent posts), who say that they've checked the Jackpot skill's effect by increasing Jackpot from 15% to 99% to 1500% to even 75000%, and still don't see a difference.
It's important to note that the testing done may be incomprehensive. In another example of testing the effects of a skill on loot in another game, it was found that the skill only worked on certain sources of loot, so Jackpot may not work on chests at all but only zombies, for example.