Certainly. A basic Mafia technique is examining the past play of the person you're suspicious of, then looking at whether their current play is more similar to their play as scum or their play as town. There is also wide knowledge (at least online) of moves that are generally "scummy," such as congratulating the doctor after he or she successfully protects, as these moves have been determined to be commonly used by scum. Of course, all of this is constantly evolving, since once something is generally known as a scumtell, advanced scum players avoid it. Further, different things are tells at different levels of play, which tends to make the game much more complicated than my above description might indicate.

That said, I think it's certainly possible to do better than chance-- my own record, at least of games that I can remember, is 4 wins to 1 loss, all as town (I have yet to be scum in my recent games).

Further, there are some situations where certain tactics have been determined, over wide periods of play, to be dominant, and applying these strategies gives you a very high chance to win. For instance, if the town has a doctor and a cop (and knows this) and also knows the scumgroup has no roleblocker, the best strategy is to stop voting to lynch, have the cop claim, and have the cop constantly investigate while protected by the doctor. The scum must then start hitting other targets in hopes of getting the doc. A truly advanced doctor will then, knowing the scum is doing this, not actually protect the cop but instead protect other members of the town in the hopes of blocking the scum's pseudorandom flailing, but a truly advanced scum player might anticipate this and try to kill the cop instead-- so there are mindgames all over the place, but dominant strategies are still known.

Generally, I feel like Mafia-- at least online Mafia-- is a rather good rationality exercise. I could expand this to a top-level post if there's interest.

Were you the scum in any of the games?

Unfortunately I play mostly as a diversion on a private site, not on mafiascum or epicmafia, so they aren't as out in the open as you'd like. If you want I can link you to a recent newbie game that I was in on mafiascum, but the number of replacements makes it a little hard to follow and it's not exactly anyone's best play either.

There are such things as Mafia techniques? I've never seen anyone do better than chance. Care to explain?

I'm not sure that doing so would be useful. It seems like normal Mafia techniques already approximate Bayesian reasoning, and formalizing it would be very challenging and IMO unlikely to offer unusual insights. That said, I'm fairly good at online Mafia and I suspect such techniques would better benefit less advanced players.

I play online Mafia but haven't attempted to use explicit Bayesian reasoning to do so.

I wonder if there aren't any group rationality games that don't seriously undermined group moral and cohesion. The last time I played Mafia people ended up crying and my relationship with my brother and cousin went through traumatic upheaval. Diplomacy is not a better option.

Trying to update even on just the well-defined data looks impossible for humans, trying to update on what other people are saying would be difficult, even with a computer. Also, it seems like there might be certain disadvantages if you turn out to be Mafia.

Has anyone been able to play Mafia using bayesian methods? I have tried and failed due to encountering situations that eluded my attempts to model them mathematically. But since I am not strong at math, I'm hoping others have had success?

And the related question: any mafiascum.net players here?

Edit: I mean specifically using bayesian methods for online forum-based Mafia games. These seem to me to give the player enough time to do conscious calculations.