Improving your chances of locking someone out with ECM

SO I'm in a corp with a bunch of miners, and we've just been war decced by a one-man corp. Most of our skills are focused on the industry and mining side of things, with not a lot of attention paid to the combat side. Since we're all a bunch of rather low-sp players, my first thought was to use ECM to give us an advantage, but I'm having a little trouble understanding how it works. I get that it's based on chance, based on your ECM strength and the sensor strength of your target, but does it stack? Meaning, do our chances of locking a guy out improve if we can get multiple people to jam a target with multiple racial jammers or multispec?