Hey everyone,
I decided to try and put numbers to how different a focus is from a calculate action. I'm not sure that I am approaching the math in the correct way and would like to hear from other people.
My process:
For attack calculate expected damage against 0 green dice for different numbers of attack dice with focus or with calculate. Honestly, rather than figure out the higher order probabilties I just used the calculator at xwing.gateofstorms.net. Once you have expected damage values for each situation just divide the expected damage (calculate) by expected damage (focus). The resulting number should (I think?) give you the percentage of the time that a focus token is identical to a calculate token.
My numbers fall out as follows:
| ATK Dice | 1 | 2 | 3 | 4 | 5 |
| ED Focus | 0.75 | 1.5 | 2.25 | 3 | 3.75 |
| ED Calculate | 0.75 | 1.438 | 2.078 | 2.684 | 3.263 |
| ED Calc/ED Focus | 0.958667 | 0.923556 | 0.894667 | 0.870133 | |
Following a similar process for defense dice:
| DEF Dice | 1 | 2 | 3 | 4 | 5 |
| EE Focus | 0.625 | 1.25 | 1.875 | 2.5 | 3.125 |
| EE Calculate | 0.625 | 1.187 | 1.703 | 2.184 | 2.638 |
| EE Calc/EE Focus | 0.9496 | 0.908267 | 0.8736 | 0.84416 | |
This obviously ignores ion/ calculate stacking shenanigans, but it seems to me that statistically they are usually pretty similar. Obviously this becomes less true as you start rolling more dice. Also, this tends to not be useful from a squad building perspective unless you are looking at some of the ships that have droid and non-droid pilots, or droid crew shenanigans.
Edit: As punkUser pointed out, my method is not quite correct. Using binomial distribution functions we can more closely approximate when a calculate is as good as a focus are as follows:
| Dice Rolled | 1 | 2 | 3 | 4 | 5 | 6 |
| Focus = Calc | 1 | 0.9375 | 0.84375 | 0.738281 | 0.632813 | 0.533936 |
For people wanting to do calculations similar to this, a really easy tool to use is the BINOM.DIST function in excel is perfect. Worth noting that the odds are identical for red and green dice since the odds of rolling an eyeball are 0.25 on each.
correcting math