According to this post, a missile with 100 vulnerability to jamming type X should have a 0 (or actually around .5 or 1) percent chance of locking on to its target. However, while fiddling around with my TC, I found that some missiles were being too accurate against the AI. So I messed with the numbers and found that a missile with 100% vulnerability fired at a ship with 100% jamming of the same type has only around a 50% chance of being deterred. The missiles in question had no other tracking vulnerabilities, such as other jamming types, asteroid tracking, or interference confusion. I tried granting the target ships the jamming both by giving them jammers with the proper stats and by giving their inherent government the jamming, but both had the exact same results.
Could anybody shed a bit of light on the situation? I'm thinking this may be a 1.1.0 thing, but lacking a copy of 1.0.10 on hand (stupid partial hard drive wipe) I can't check.