I'm sure that someone must have done the math on this one by now? If you are strictly looking at defense, which is better, a focus or an evade? I'm guessing that it comes down to how many evade dice you are using, as in, you are much more likely to roll two focuses on three evade dice, so focus would be better for a TIE Fighter than for a Bomber.

Specifically, I'm looking at putting Jan as crew on a Bwing. When flying in formation with Biggs, she can give Biggs an Evade token, which will keep him around longer to soak up the shots. My worry is that with two dice, he would be better off holding a focus for defense.

Well with 2 dice he's better with the evade and having a 6/8 chance of naturally rolling another. 3 or even 4 dice though (say if the shot is obstructed) then consider focus as obviously it has inherent offensive bennies. The nice thing is you can choose so its not set in stone.

range, natural green dice, and can you attack, can they attack dynamic all play a part in the great debate...

In the large majority of circumstances, looking just at defence the evade action is better than a focus.

As other posters have said, the situations are too varied to consider all possibilities mathematically, which is why this is a great game to play over and over!

Evade action ensures that you are guaranteed to get at least one evade result, with lower chances of rolling more evades (37.5% chance per dice)

Focus drastically improves the chance of rolling an evade result (62.5% per dice) but that creates the potential for ending up with no evades at all, as I'm sure we have all seen and cursed the blanks for!

As with any dice game, success lies in understanding the odds of success and failure in any situation.

Focus has a far greater positive impact on your odds if you are rolling more dice, so I tend to use Evade on a 1 or 2 Defence dice ship and Focus with 3+ unless they are 1 hit away from destruction and need that guaranteed protection.

Since the attacking dice have a greater chance of hitting than a defender has of evading, the best form of defence is always to stay out of the way of attackers and kill them first!

With Biggs, definitely an evade.

Look at it this way - you're only going to do 'better' than an evade token if you roll two focus results on the same roll. Which isn't going to come up often. If you're only getting one focus result, then the one hit an evade token would have cancelled does the same for you. And you know you can spend it when shot at, rather than just hoping you have the option.