Speculating on what the final statistics will be that may determine your ending. I'm guessing that we get into a situation ooga booga booga and the situation will autoplay and certain things will happen based on choices made throughout the game, like if you conditioned Clem then she'll save everyone YEEH.
No rly, game mechanic wise I'm seeing this:
1. Honesty level - how honest you've been throughout
2. Self-gratification - how often you've been self-serving (keeping food for yourself, choosing aggressive options)
3. Clem Treatment - whether you pampered her (kept telling her her parents were alive, saying that things will go back to the way they were, giving in to her choices such as not taking supplies from the van) or if you conditioned her for the apocolypse (honest with her throughout)
4. Clem Exposure - how often you exposed Clem to acts of mercy or aggression: Did she see you kill the farmer? was she there when you either spared or left Ben? What reason did you give to Clem when you either kept or left Lilly? Etc.
5. Deaths: how often you killed non-walkers or gave pity-deaths.
6. Leadership - How often you either made a decision that the group went with or if you remained neutral as often as possible.