Originally, Pirate Attack was first thought to be spawned by having Civil Liberty + Investment states. This was a logical, if incorrect idea, as a natural "terminator" of a prolonged positive state. But then Pirate Attacks started happening in places without such states. There's also been some suggestion (happy to be corrected) that Pirate Attack can "spread" like Outbreaks if unchecked.
I don't think anyone's suggesting that PA isn't triggered by player activity, but what that specific activity is, if any, is not known. I'd defer to Ian again here, as he's probably got a lot more stats on it than I do (which is zero).
My belief is that it's either "any activity at all" or "any positive activity", with a threshold to reach. It's very hard to run more controlled tests on it because of the 14 day invisible pending period, and Colonia doesn't have any 'clean' systems for that sort of test anyway.
Obviously the factions which attract high activity tend to attract lots of positive transactions, so the
correlation with Investment and Civil Liberty is pretty strong - but it's because they have a common cause, not because those states cause Pirate Attack directly.
I don't see any sign that Pirate Attacks can "spread" directly - but they may well appear to because Pirate Attacks attract core miners, which may then increase the activity level in nearby systems too. (For that matter, I'm unconvinced that Outbreak can spread directly either [1])
[1] My current working theory for Outbreak is that it is increased by two things:
- negative transactions (or maybe ship losses?) of a certain volume
- those missions which say +Outbreak
and this combined with it also having a 14-day invisible pending period and being blocked by Pirate Attack is sufficient to make it look clustered just through player action. This is somewhat speculative but fits the data I have.
But there doesn't appear in general to be a mechanism where a faction in Outbreak is more likely to get Outbreak in its other systems, or an Outbreak in one faction in one system is more likely to cause other Outbreaks in that system or nearby systems.
I'm actually quite impressed by both the PA and Outbreak states - they're driven like the rest of the BGS solely by player activity, so far as I can tell, but wth sufficient indirection that in
most cases it's impossible to predict where and when they'll appear next.