Saturday, April 25, 2009

Acknowledgement of comments received

Just a brief post acknowledging that I have read two comments made in the past few months when I wasn't doing anything with this blog.

Comments on data table header translations of Lodeguy's data. Technically, I did not really translate anything as I don't know Japanese (I didn't say I was translating anything), barring being able to read katakana, simple phrases and basic kanji.

Comments on my criticism of an alternative analysis of paralyze data. I do not have issues with the original analysis. The secondary analysis I nitpicked past its veneer of soundness. I made this post on a "whim," which kinda goes to show I seek out "fun."

Thursday, April 23, 2009

Expected magic damage in terms of accuracy - more parlor talk

In some sense, having to hoard magic accuracy for so-called high-resist targets when nuking (or enfeebling, etc.) is an all-or-nothing proposition for various reasons I just made up that may incidentally be shared by others. One, these high-resist targets have such high magic "evasion" that it is completely untenable (from experience or whatever) to nuke with the same equipment you would use for Ebony Puddings. Two, even if the target of interest is not quite as resistant as, say, a wyrm or sky god, it can be difficult to ascertain what amount of magic accuracy is acceptable to reach some threshold (say 90% acc.) without personal experience (or the experience of others). Three, compared to mindless melee auto-attacking and WSing, nuking specifically is inefficient from the standpoint of theoretical damage dealt in the "long run" (MP being an important limiting factor), so it seems pragmatic to accept unconditionally the trade-off of lowering maximum magic damage for fewer resists when there is any doubt.

If there comes a time where it is easier to ascertain the magic evasion of any mob of interest (probably never given the FFXI "team's" fetish for making basic game mechanics as opaque as possible, and lack of information sharing among the "playerbase"), perhaps it can be useful to quantify the difference in overall magic damage between a "high-resist" setup (with the purpose of maximizing magic accuracy) and a normal setup for resistant NMs and whatnot. But realistically this is just another parlor talk.

A long time ago, I argued that levels of resistance for a single "nuke" can be modeled by a one-parameter categorical distribution, with the parameter being the probability that a nuke is not resisted at all (full damage). This probability will be called "overall magic accuracy" for the remainder.

To reiterate, the distribution can be described as

no resist: π
1/2 resist: π(1-π)
1/4 resist: π(1-π)2
1/8 resist: (1-π)3

This assertion was based on prior observations by me and others that multinomial count data for nukes, categorized by level of resist, seemed to conform to such a pattern. (I will not discuss the speculated motivation for the programmers to use this model, assuming it is true.) If this is a reliable model, it seems reasonable to think about the effect of overall magic accuracy on magic damage in terms of expected value.

Ignoring rounding, let X be the actual damage of a nuke (subject to being resisted) with unresisted damage D. The expected value of X can be expressed as

E[X] = D[π+0.5π(1-π)+0.25π(1-π)2+0.125(1-π)3]

Based on this expression, overall magic accuracy can be thought of as attenuating the unresisted damage of a single nuke in the long run, multiplying that damage by some factor less than 1 that is a function of π. Therefore, in making some assessment of overall magic damage as a function of magic accuracy, we don't have to consider the actual distribution of resists given π, just as players calculating physical damage don't consider the distribution of pDIF given a ratio of attack to defense.

Just as magic accuracy attenuates unresisted magic damage by some factor less than 1, magic attack bonus (MAB) amplifies magic damage by a factor greater than 1. This is illustrated and summarized with the following graph plotting these factors described (for magic accuracy and magic attack):



As you can see, when "long run" magic damage is considered, there is decreasing return to overall magic accuracy, π (the expected value computed earlier is a third-order polynomial with respect to π), and constant return to MAB. The endpoints also make sense, too. If you happen to have 100 MAB, your overall damage is twice as high. If you happen to have 100% overall magic accuracy (recognizing that this is impossible in FFXI for nukes), then there is no attenuating of your potential magic damage.

Using the model for levels of resistance I described, it is possible and simple to estimate the percent change in long-run magic damage between two equipment setups of interest. Suppose you have a normal setup with +70 MAB such that you know will achieve 60% overall magic accuracy on some target of interest (this means in the long run 60% of your nukes will be unresisted) and you are interested in assessing whether utilizing your "high-resist" setup is worth the tradeoff in potential damage. Suppose your high-resist setup has +63 MAB and +26 more magic accuracy than the normal one.

At this point, there should be no need for quantifying the relative performance increase, but perhaps you want to quantify it anyway.

Since the magic damage "formula" is just multiplying various factors together, it is easy to calculate a percent difference that is independent of base damage, INT, weather effect, etc. (all of which could be considered constant). One needs merely to identify the multiplicative factors associated with MAB (+63 and +70) and m. acc (60% and 86%). Through direct calculation,

(1.63)(0.924757)/[(1.70)(0.752)] - 1 = 0.179

In the "long run," the overall damage using the "high resist" setup will be almost 18% higher than that using the normal one.

Again, is this useful or practical? Not really. But it could serve as a theoretical framework for "theorycrafting" (oh how I hate MMORPG-related jargon).

Tuesday, April 21, 2009

One more time

I am fairly amused that the conclusions from lodeguy's magic accuracy experimentation and my data analysis have been used to support the shibboleth of "320 skill/120 INT" for direct-magic damage (just browsing FFXI forums periodically). Maybe "shibboleth" is too strong a pejorative, since at least this rule of thumb acknowledges that INT contributes to overall magic accuracy (even though this acknowledgment seemed to be supported mainly with anecdotes and collective experience rather than formal data collection).

Should we really care about attaining 120 INT?

As you may recall, lodeguy gave us data that suggest (informally) a critical point for ΔINT (caster's INT minus target's INT) that "connects" two distinct regimes of rate of change of overall magic accuracy with respect to INT. To summarize, before ΔINT +10, the rate of change is estimated to be 1% per 1 INT (actually a little less from statistical significance testing), and between ΔINT +10 and ΔINT +30, 0.5% per 1 INT. I only emphasize this range because there is no data to show what might happen beyond ΔINT +30. (Moreover, there was no data to suggest, as far as I can recall, the effect of INT below 50% overall m. acc. But, realistically speaking, no one is ever going to investigate these issues. This is the best we will ever get, probably.)

With that in mind, it might be interesting to get some sense of whether 120 INT is generally suitable in "endgame" to reach the second ΔINT range with the slower rate of change. To do this, one must compare 120 INT to the INT of various "endgame" mobs.

Regrettably, information about mob INT from English-language sources is either poorly documented (sequestered in obscure FFXI forum posts) or almost non-existent (seriously, does anyone give a fuck about anything other than Ebony Puddings?), and this annoyed me to the point that I attempted to calculate the INT (as well as magic defense bonus, or MDB, and reduction of magic damage taken, or MDT-) of various mobs that I faced over the past few months to get a sense of whether I was surpassing ΔINT +10 most of the time. As I said in the last post, magic damage is deterministic (level of resist is random), so it should be fairly straightforward to calculate mob INT in many cases. Of course, I could have made calculation errors or overlooked level variability for specific mobs. I will leave it to others to verify or refute my calculations.

There isn't much variety in what I do in FFXI, though. All I have is data for mobs in NW Apollyon and those for various ZNMs. First, NW Apollyon:

MonsterINTMDBMDT-
Bardha75
0
0
Pluto82
0
0
Mountain Buffalo
60
0
0
Apollyon Scavenger
620
0
Gorynich72
0
0
Kronprinz Behemoth
74
0
0
Kaiser Behemoth
???
???
???

As you can see, most of the "normal" mobs have low INT so that ΔINT +10 is easily cleared. As for Kaiser Behemoth, I didn't gather enough information, but I am pretty sure it possesses some combination of MDB and MDT- traits. I also collected similar data on some ZNMs I fought several months ago:

MonsterINTMDBMDT-
Lil' Apkallu
60
0
1/4
Verdelet
115
0
0
Experimental Lamia
89
0
1/8
Mahjlaef the Paintorn
1120
1/4

Cheese Hoarder Gigiroon
81
0
0
Vulpangue
78
0.20
0
Dea
62
0
0
Iriz Ima
70
0
0
Gotoh Zha the Redolent
92
0.28
1/8
Tinnin
85
0.20
0
Achamoth
65
0.16
0

Here, MDB is reported in terms of amount above 1.00. MDT- is reported in terms of fractional reduction of magic damage.

Other than Verdelet (an imp) and Mahjlaef the Paintorn (a soulflayer), all of the ZNMs have INT such that ΔINT is well above +10. Therefore, from the standpoint of optimizing overall magic accuracy (given what we know), it seems practical to exchange INT in excess of ΔINT +10 for elemental magic skill or magic accuracy. In particular, this could be useful for Tinnin, which seems to have higher magic resistance than the "lower-tier" ZNMs (probably a result of level difference) despite having "only" 85 INT.

Moreover, there could be some patterns to mob INT despite the limited information available. Beastmen and other "sentient" mob types (particularly soulflayers and imps) could have higher INT in general than other types. Magic users have higher INT in general than non-magic users (I will treat this as self-evident).

But concerning the main question, it appears, at least for most ZNMs that are worth nuking and mobs in NW Apollyon, that ΔINT +10 is surpassed most of the time. If you happen to get close to 120 INT incidentally, that's great, but not necessarily at the expense of possible improvements to magic skill/magic accuracy. For example, Dea has only 62 INT, but it is still prone to resisting Thunder IV (compared to Blizzard IV). Therefore, it would be appropriate to use Sorcerer's Petasos instead of Demon Helm +1 for the sake of improving accuracy.

None of these mobs even have INT above 120, so it's not like you would get much of an improvement to resist rates whoring INT (such that ΔINT +10 is satisfied) compared to whoring magic skill/accuracy (all things being equal).

So what about beastmen "kings" and HNMs? Bahamut ("The Wyrmking Descends") is reported to have 115 INT (from Studio Gobli, if you can actually find the documentation). (Bahamut is sentient, right? Check.) Also Jormungand is reported to have 120 INT (also from Studio Gobli). (Perhaps the example of Jormungand motivated the 120 INT figure?) Other than that, I have no other information.

Anyone can calculate mob INT, but...

... magic defense bonus (MDB) and reduction in magic damage taken (MDT-) can get in the way of calculating INT. These factors may play a role in determining overall magic damage for things like Sarameya and Tyger. Without knowing MDB and MDT- and considering the incessant flooring involved in these calculations, it is somewhat difficult to arrive at a unique set of MDB/MDT-/INT that allows you to calculate magic damage exactly without using formal optimization methods, and I am not interested in doing that.

However, this post offers some very useful facts to determine what exactly a mob's potential MDB or MDT- is. In particular,
  • 1000 Needles is not affected by MDB.
  • Quick Draw is not affected by MDT-.
  • Damage calculations for both are independent of mob INT.
Unfortunately, I don't have access to blue mage or corsair, but these tools would be very useful if I had access to them. Practically speaking, it doesn't seem particularly appropriate to do this kind of testing during "serious" events (how seriously do you take Proto-Ultima?), but your mileage may vary (enough with the cliches!).