Mathematical ExplanationWarning, lots of math ahead (duh).
Assumptions and Set ValuesDuring the complete calculation for the purpose of this thread, the following numbers are assumed:
Expected HP remaining on a non EM win: 50% of max HP (same as UEI)
Turns per Skip: 1 (yes, that might be on the high side, but it's plenty profitable that way already, I don't really want to lower it, to stop the skiplists from becoming even longer).
Turns per Hour: 333 and 250 (results given for both values)
The following values are used for spinprofits (I ran the simulations in xenosim, just to have 'something' for now. It is can easily be changed if someone comes up with better (more accurate) numbers):
The following are also assumed:
Turns to Lose is 75% of Turns to Win per god. This (arbitrary) number I based on the ratios of TTW and TLL from older tests (it was 74,44%).
The TTW for a god without games won (and thus without a Turns to Win entry) is assumed to be the average of the other TTWs.
Initial CalculationsFirst it calculates Turns to win per god (Total turns to win/Wins), or for gods without any wins, it uses the average of the other gods. Then it calculates the assumed turns to lose for that god (TTL = 0.75 * TTW). Based on those two is calculates the TTF for each god as a weighted average: TTF = (TTW * Wins + TTL *Losses)/(Wins+Losses)
Profit per Game and UEI[FG]
Next, the profit per game per god is calculated based on the wins, losses, EM's and spin profit. This follows the general UEI calculations, with a few changes:
First, since we are calculating profit per game, instead of per hour, we don't have have to use TTF or TPH yet. Aside from that, some changes had to be made to the formula, because of the differences between FG's and the other opponents.
PPG = Profit per game (per god) = (W*60*19/24*(1+EM/W*(48/19-1))*(1+XHP/200)-30*L+W*SP)/(W+L)
This is calculated for each god separately (using the numbers of that god).
The average profit per game per god, divided by the average duration of a game (in turns), gives the average profit per turn. Multiplying this by TPH gives profit per hour. Because there are averages on both sides of the division, it's possible to use sums instead, which simplifies the later calculations.
Sum of PPG / Sum of TTF * TPH = UEI
SkipsEssentially, factoring in skips is very simply: you set the profit per game for each skipped god to -30, and the TTF for that god equal to the turns per skip (TPS, assumed 1), and recalculate the UEI using the above formula.
Recall, so far we are using:
Sum of PPG/Sum of TTF * TPH = UEI
We are interested in knowing for which god a skip is profitable, and for which it isn't. Turns per hour isn't relevant, if it's more profitable per turn, it will also be more profitable per hour, so that part is omitted from the formulae for now. (once we find the optimal profit per turn, we can simply multiply by turns per hour).
Sum of PPG/Sum of TTF < (Sum(without god X) of PPG – 30)/(Sum(without god X) of TTF +TPS)
For now we are only interested in the sign in the middle: is it a less than or a greater than sign. This is where CuCN came in, and introduced the
mediant inequality.
Sum(Without god X) of PPG – 30 = Sum of PPG – 30 – PPG(god X)
Sum(Without god X) of TTF + TPS = Sum of TTF +TPS – TTF(god X)
Looking at this, it seems like we should be able to use the mediant property to do something useful, and that turned out to be right, using the following 2 fractions a original fractions:
(Sum of PPG – 30 – PPG(god X))/(Sum of TTF + TPS – TTF(god X))
Skip Index = (PPG(god X) + 30)/(TTF(god X)-TPS)
The mediant of the two is
([Sum of PPG – 30 - PPG(god X)] + [PPG(god X) + 30])/([Sum of TTF + TPS – TTF(god X)] + [TTF(god X) – TPS]) = Sum of PPG/Sum of TTF
Because of the mediant inequality we know that the mediant is always in the middle of the two, in other words. If and only if:
(PPG(god X)+30)/(TTF(god X)-TPS) < Sum of PPG/Sum of TTF
then
Sum of PPG/Sum of TTF < (Sum(skipping god X) of PPG - 30) / (Sum(without god X) of TTF + TPS)
Or, in other words if the skip index is smaller than the average profit per turn, it's profitable to skip that god.
Therefore, we are going to sort by skip index, and cumulatively skip in that order, adding one additional god to the gods already skipped, starting with the god with the lowest skip index.
Skip reliability checksThe above procedure is accurate (or well, as accurate as it gets under the assumptions made), but that doesn't mean it's optimal. After all, we are dealing with a set of statistical data, so there is going to be a certain margin of error. In most of the studies in this board that isn't a problem, because you win one more game against one opponent, and then lose that game against another, big deal. In this case it can affect the ratings significantly, because that 1 lost game might push that god over the edge, so that he now ends up on the skip list, which might be a bit of an overreaction all because of 1 game. For this reason, I built in some additional checks. These two checks don't alter the UEI reported (since that is the optimal one), but they do determine the secure version of the skiplist.
The first check is actually 58 checks in 1. I asked myself the question: what if you played 1 more game with this deck, how could that affect the current ratings?
Hence 58 checks in 1: there is 58 possible outcomes to that additional game, win or loss against 29 different gods. So, it calculates the altered ratings if that additional one game would have been a loss or win against each god, and concludes per god if he should be skipped or played with that one additional game taken into account. If a different conclusion is returned for losing compared to winning, the god is marked as ‘fluctuating’ (too close too the breaking point to tell, a single game can swing the rating from skip to play or play to skip, likely because of a small number of games played (remember, skips are excluded from the stats): if you only have 2 games against a god, there is only 3 possible winrates: 0%, 50% or 100%. It’s clear that this isn't going to give very accurate winrates, thus not very accurate skip recommendations, which then likely results in an ‘fluctuating’ rating).
The second check checks something different: even if it is theoretically profitable to skip all games against a certain god, I probably won't do if it only gets me a very small increase in UEI. Thus, it checks if the UEI after not skipping that god (and all gods above this god in the listing), is within 2% of the optimum, if it is, the god is marked as ‘Marginal’, changing the behavior against these gods (still cumulative along the ordered list), from skip to play, changes the UEI by so little its not relevant, therefore I’m not giving a strict recommendation on these gods. Yes, unlike the ‘fluctuating’ marker, this one is only applied to gods listed as skip. (Nobody is going to skip MORE gods because it only lowers their income by 2%), and if a god is both ‘fluctuating’ AND ‘marginal’, ‘fluctuating’ takes precedence.
Skip ListsAll gods skipped to reach the optimal UEI are included in the optimal skiplist. All gods still marked skip after factoring in both the fluctuating and marginal check are included in the secure skiplist.