Random wrote:Llenlleawg wrote:Now, since we have agreed that, in the end, the
actual discrepancy between the two systems overall is relatively slight, and since any adventure assuming one system in its design would not disadvantage players who had presumed the other, might we be willing to engage in a little truce?

Nope, I'm not convinced. I'll do the calculations later and let you know how it turns out.
Fine, then. Here we go, using a cleric (since his hit dice are easy to calculate and compare [1, 2, 3]).
At first level, what are the odds for the range of hit points in the two systems? For first level, the odds are the same.
So, what about second level? We'll look at three scenarios. In A, our cleric had only 1 hit point at first level, in B he had 3 hit points, in C he had 6 hit points.
As expected, the minimal hit point character using the Whitebox method is more than likely to pull past his minimal hit point peer using the “don't reroll all the dice” method (the "other" method throughout), from 1st to 2nd level. Indeed, he has a 41.67% chance to have more hit points than his peer even possibly could (i.e. 8-12).
For just below average (3 hit points), the difference is not so stark. The Whitebox character has a 75% chance of falling within the same range (4-9 hit points) as his peer. His odds of getting 8-10 hit points are equal to his peer's odds of 8-9, and while he does have a 16.67% chance of getting hit points higher than his peer possibly could (10-12), he also has an 8.33% chance (1:12) of not increasing in hit points at all, i.e. having a lower value than possible for his peer. [Note that just above average, at 4 hit points, the odds tip in reverse, namely, only a 8.33% chance to be out of his peer's range (11-12), while a 16.67% chance (1:6) to be below the minimum score of his peer (i.e. remaining at 4 hit points). If one could actually roll 3.5, this would mean that there is a 75% chance of having the same range, with a 12.5% chance to fall below and a 12.5% chance to go above the peer's range.]
At maximum hit points, we get a very different picture, not precisely the inverse of the minimum scenario, but still not great news for the Whitebox player. The Whitebox player has only a 58.33% chance to fall in the range of his peer, and while his peer has a full 50% chance to have 10-12 hit points, the Whitebox player has a mere 16.67% chance (1:6) for the same range. Indeed, the peer has a full 16.67% chance for maximum hit points (12), while the Whitebox player has only one-sixth the odds, namely 2.78% (1:36). At the same time, he has a full 41.67% chance (5:12) of remaining below the lowest possible score of his peer, i.e. remaining at 6 hit points.
Now we'll try for 3rd level, i.e. 3d6. In scenario I, we'll look at minimum at 2nd level (2) advancing to 3rd, for scenario II, we'll see average (7) advancing to 3rd, and for scenario III, we'll see maximum (12) advancing to 3rd.
As we might expect, the same patterns appear, but more starkly. In scenario I, there is no contest. A minimum hit point Whitebox character at 2nd going to 3rd has only a 25.93% chance of being in the same range as his peer (3-8 hit points), giving him just under 74.07% chance (<3:4) of having 9-18 hit points. Indeed, he has a 57.87% chance, i.e. more than double, to be a full d6 higher (9-13 hit points), and a 16.20% chance of the highest hit points (14-18).
For the average score (7) advancing to 3rd, as above, things level out considerably. The Whitebox character has a 67.58% chance (>2:3) of being in the same range as his peer, viz. 8-13 hit points, with the highest odds (25% chance [1:4]) being towards the middle (10-11) as opposed to his peer's equally good chance of scoring high as scoring low. On the other hand, the Whitebox character is as likely (16.20% [<1:6]) to be below the lowest possible for his peer, remaining at 7 hit points, as he is to go beyond his peer, with the odds of maximally high scores (to get 18 is 1:216) being especially remote. Compared to the scenario above, this means that the Whitebox character will still tend to have the same range as his peer if his base score is average, and is no more likely to exceed his peer than he is to fall below his peer's minimum, although as he advances in level, he will become relatively more likely to fall below or to exceed than to fall in the same range.
Finally, the maximal scenario is also no contest, but the shoe's on the other foot! The Whitebox character is now 74.07% likely to remain at 12 hit points. That's right, there are 3:4 odds that he does not gain any hit points at all and falls necessarily behind his peer, who would have a minimum of 13! Moreover, his peer is now fully thirty-six times more likely to have 18 hit points than the Whitebox character (and twelve times more likely to have a 17, etc.). This pattern will of course continue as levels increase, so that, given two characters with maximum hit points, the Whitebox character will be increasingly likely not to gain any hit points at all and to fall back towards the average while the peer will continue to have reasonably good odds (50%) to remain above the average, and indeed to remain high.
What does this all show? Rather what we both knew before the number crunching. As we noted, the Whitebox system tends to “repair” low rolls, so that as levels increase, the odds of such a character not having average hit points diminishes. Average hit point characters will show increasing chances both of excelling and of falling behind as the number of hit dice increases. Nevertheless, high hit point characters will be increasingly and more powerfully held back and incline more to the average. The punch line? Whitebox characters will over time end up with average hit points. Not only that, any given character, the longer he is played, even if he has a high total at any given level and certainly if he has a low score at any level, is most likely in the long run to end up average.
The “other” version, by contrast, results in lags and gaps that become harder and harder to bridge. A low hit point character, the longer he rolls low, will find some hit point totals forever out of his grasp, and even average hit points a receding possibility unless he starts to roll better. Likewise, high-rolling characters will be less likely to be undone by low rolls, and will tend to remain on top of their game, apart from a string of low or middling rolls.
So, while all Whitebox characters will tend to the average individually (and not just by averaging them across a large sample), this is not so with the other method. Granted, Whitebox allows a little variety, and occasional lucky rolls, so that it does not resemble systems without any randomness to hit points (e.g. D&D 4e). Even so, given that many people house rule such things as maximum hit points at first level or rerolling any 1s or 2s for those using the “other” method, Whitebox will surely produce nothing out of the ordinary, and indeed, over the course of levels, will tend to produce average hit points across the board.
Quod erat demonstrandum.