Live Letter XXX Discussion Thread

[Kaze3434]

There are two different (yet related) concepts that people have been discussing here, and it's important not to confuse them.

The first, which we'll call event probability, represents the chance of any one isolated action happening in a certain way. In the map dungeon scenario, this would be the chance when opening a door that you'll get the correct door. As I briefly mentioned in my original post, this may not necessarily be 50% depending on SE's exact implementation, but it's easier to assume that it is. What this means is that any time you clear a room and go to open the door to the next room, you'll always have a 50% chance of your chosen door being the correct one. That is, regardless of whether you're opening the door to the second room or to the seventh room, you still have a 50% chance of being right.

Another way of representing this is to say, "Given that I've already reached the N'th room, I will always have a 50% chance of reaching the N+1'th room."

This should not be confused with the other concept, cumulative probability, which represents the chance of a given series of events happening in a certain way. In the map dungeon scenario, this would be the chance of reaching a particular room without any pre-conditions. What this means is that if you wanted to figure out your chance of reaching, say, the third room--before you even pop the map in the first place--you need to consider it in the context of the chain of events that will lead you to that outcome. For that particular example, it's very straightforward to derive the cumulative probability using the individual event probability form discussed above:

You have a 50% chance of having the portal spawn once you beat the initial pop.
Given that you had a portal spawn, you have a 50% chance of selecting the correct door from the first room.
Given that you made it to the second room, you have a 50% chance of selecting the correct door from the second room.

Therefore, the probability of making it at least as far as the third room is the product of the individual event probabilities, or (1/2)^3, which works out to 12.5% for any given map. Of course, this doesn't mean that if you did 1000 maps, you would make it to the third room exactly 125 times, but any given sample set should be close to that proportion--assuming SE is using a reasonable PRNG algorithm in the proper way; all bets are off if that isn't the case.

thats the problem. SE RNG is stupid for the most part. small example from yesterday is when i was melding some materia for a friend. went thru 8 materia at 26% before one finally went in, and then the next chance was 10%. it went in on the second one. for me, i have stopped using the collective probability for this game, because its largely depressing, and at times, useless because rng gonna rng.