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Thread: Teaser: Introduction to advanced healer/tank evaluation

  1. #1
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    Teaser: Introduction to advanced healer/tank evaluation

    This is a teaser to the full version of "advanced healer/tank evaluation". Since it would take very long to write the full version, and not all the math have been finished yet, I would like to know whether people would like to get the full version, or if no one really cares about it. Also note that I would prefer putting a full version up in a bit different version, so formulas and graphs can be included much better.

    Have you ever wondered how good performance a healer or tank are showing you? We all know that coming up with some simple form of evaluation of healers and tanks arenít all that easy, especially since their group function is much more complicated than the simple: pull as much dps as possibly, without pulling aggro and doing it on wrong targets. But how do we come with some form of evaluation of tanks and healers? And is this important at all?

    So why would this be important, simply because evaluation is a powerful tool in testing setups (both gear, spec and group composition wise) and tactics, and will also serve as comparing between people for (pug) raid spots, so you have an idea whether you invited a overgeared fool or a undergeared top player.

    I might have already said this, but there is no simply way to give you a meaningful single compromised number for how good or bad a healer or tank is. We can however try to do something else: Describe parts of this. Since treat for tanks and general gearing already got plenty of ways to get described in practice (you just watch a data collector, maybe with live feed like omen or recount). Instead we will be looking at the other aspect, the mathematics of survival.
    Before I start out with the following, I am going to put up a warning: This is NOT for everybody, since it will require understanding of several more complex mathematical forms, mostly in the form of calculus of standard and quantized functions. So let us start.

    The first thing I am going to do, is tell you what precisely we are looking at: we are looking at the movement of the hp bar for a tank, in a non oneshort/fast burst scenario, since that area will need some more work to make the same formulas useful, and will therefore not be including in this first teaser version. I guess I have prolonged it long enough now, so lets start by defining 3 functions, a discontinual function for the incoming damages called D(t), a discontinual function for incoming healing called H(t), and a quantized function of standardized health missing compared to the max health (standardized in such a way, that tank death happens at a value of 1), called Hp(t). The first thing to mention, is that Hp(t) describe how much behind the healers are on healing the tank, supposing the idea of keeping tanks with topped up or close to it for the purpose of countering bursts. These 3 functions got a relationship much similar to the second law of Newton:

    D(t)-H(t)=I*DeltaHp(t)


    Yes I am having problems with getting math properly into this forum, and if anyone got an idea how to import formulas, feel free to tell me how, I for one would love to see it able to import a whole pdf article, or something like that. The Delta in front of Hp(t) tells us that it is the change in Hp(t), while I describes the inertia of the Hp(t) function, which funnily enough is current maximum health of the tank. Now we have 3 functions which describes the motion of the health of the tank, but so what, that havenít really showed us anything useful yet. But here is the difference, now that we have some functions, we can call in some mathematical descriptions of these. Throughout the rest of this, I will be assuming that you have somehow collected a dataset for an encounter, where you have all incoming damage and healing, and also the max hp and any temporary changes in it, since almost all of the following will be about how to get information out of that data. Letís start by assuming Hp(t) has values distributed close enough to the normal distribution to make that a viable way to describe the function. With that we can calculate the mean (mu) and the deviation of the mean (sigma), which are given by the following 2 formulas:


    mu=(integral from 0 to T) of (Hp(t)*dt)/T=(Sum over encounter) of (integral from t to Deltat) of (Hp(t)*Deltat)/T=(Sum over encounter) of (Hp(t)*Deltat)/T

    sigma=((integral from 0 to T) of ((Hp(t)-mu)^2*dt)/T)^0.5=((Sum over encounter) of (integral from t to Deltat) of ((Hp(t)-mu)^2*Deltat)/T)^0.5=((Sum over encounter) of ((Hp(t)-mu)^2*Deltat)/T)^0.5

    Since this would be quite tendentious to calculate by hand, it is suggested putting these fomulas in the code of a program capably of working with numbers, which addons should be able to do. It should be mentioned that when writing the code for the above it becomes significantly easier when you have a dataset, as the integrals and sums easily can be calculated through relatively simple means of coding.
    Now you may be wondering what exactly you can get out of those 2 numbers. Letís look at the simple of them first: the mean or mu. The meaning of the mean is to describe on average how far behind the healers are on the healing on you. What that translates too, is how good the healer/tanks are at keeping the tanks health height on average over the fight, this especially tells you if the healers are having trouble with dealing the overall damage on the tank, and how might also give you an idea of how good the healers are at keeping the tank topped off or almost topped off. For the specific values, a value lower than 0.2 will indicate the average incoming damage on you arent that much of a problem for the tank/healer combination, and is what you would be expecting on farming trash and non hard-hitting farm bosses. On the other hand, if the mean gets up around 0.4 or above, it indicates that the overall damage on the tank is quite heavy, and the healers are having troubles keeping the tank on height hp. A evaluation with a (relatively) height mean, often signifies one or more of the following:

    1)The tank are having low migration (combined armor, avoidance static, cooldowns and such), and it could be an idea to work on this section to make the healers life considerably easier.
    2) The healing might be spread a bit too thin. So that healing on the tank gets considerably delayed.
    3) The healers are relatively slow on getting healing healer to tank, meaning that he stays on low hp for long, and especially if the healing is slow on topping the tank up after such.
    4) The tank having either plenty of health (which means the healers arenít very concerned about topping the tank off) or have very low health, so that the percentages are of health is very height, and therefore moving the the percentage he falls to when taking similar damage (as the inertia is lower).

    However it isnít fully guaranteed that it is one of those problems, but chances are that it is one or more of them. Also notice that migration has a much larger factor in this than tank health, and that tank health only becomes significant if there are huge derivations from the design of the encounter (such as a 35k+ unbuffed tank going to heroics or a 30-34k unbuffed tank going to icc 25), and even then it is guaranteed to be a significant factor.

    Now lets take a look at the meaning of the deviation or mu. First of all, the deviation describes how spread out the tanks health is around the mean. As the deviation tries to describe how long time the tank have been an given health area around the mean. More precise, the tank have been roughly 68% of the time within the range 1*sigma, roughly 95% of the time within the range of 2*sigma and around 99.5% of time within the range of 3*sigma. It should be remembered that these statistical numbers, and should be treated as so. If we for instance take a 10 min fight, which gives us 600 seconds, then the tank will spend 408 of those within 1*sigma range, and 192 seconds outside it, while he spends a stunning 30 seconds outside of 2 sigma range, and still 3 seconds outside the sigma 3 range. Since it is not sure whether that those 3 seconds will come or not, it could still easily happen, and will often represent the worst moments of the fight. Out of this it can be concluded that for a relative safe encounter it is clearly advisable to have 3*sigma+mu<1, since that will significantly reduce the chance of wiping due to lack of healing in conjuration with bursts. The interesting thing, is the following which can be used to do a rough calculation of chance of tank death with the corresponding healing, which can be written as the following:

    Kappa*sigma+mu=1 <=> Kappa=(1-mu)/sigma


    Here Kappa gives you the number of sigmas where the tank are on going out of the range of life, therefore it also describes the chance the tank has to die. As mentioned above this should preferably be above 3, and even a value between 2-3 means that you are having tank on the verge of dying very often, if he already hasnít. Generally if the Kappa is close to 3, and especially if it is lower, there are the following things to be noted to deal with this:

    1) The tank should consider using a more EH heavy gear setup/spec, since this will directly reduced the sigma
    2) The healers might be favoring big heals, which could be dangerous, and should be consider if it would worse using heals which will have a lower chance of causing big fluctuations in the tanks health.
    3) The tank should make sure his cooldowns are managed to avoid the lower health areas/spike damage times, since they might be a problem.

    It should be noted, that a Kappa around or lower than 3 doesnít directly gives you x% chance to wipe, since that is encounter specific, especially if the fluctuations are just because the healers are using big heals in a relatively safe environment. It can also easily be caused with different phases where the tank has different means, which causes a problem when trying to calculate over the entire fight.
    The deviation itself also describes something else than the tanks chance to die during non one-shot bursts (bursts over several seconds, such as no misses streak and late healers). Under the right circumstances, meaning where the functions value distribution is close enough to the normal distribution), sigma can tell you something about how much damage the tank should expect to take before getting healed for it. Most of the time, he would be going from around the upper bound mu-sigma (as the hp function is going reverse to health) to mu+sigma, which means a difference of 2 sigma. This is very rough, since it has heavy correlation with the predictability of the damage, the avoidance and the specific setup of mu and sigma, but we can still use it as rough estimate. Since this tells something about when the necessary heal on the tank will be coming in. The cause to a hight sigma on fights, where the burst problems are low and predictability of the dame is low, then it is often one of the following:

    1) The tank is taking heavy damage, which causes a lot of movement of the Hp(t) function, which enviably lead to spread out values and therefore a height sigma.
    2) The healer(s) are slow to fire off the heals on the tank, which might be because they use big heals and/or the incoming dps is low, though it may also be because the healers are just generally slow.

    This is about how much I was thinking of including in this teaser. I amid it have become long, but there are much more information that be derived from the above functions, by doing something else than just simply calculating the mean and its deviation. Things I got on my list, are a mathematical description of the unpredictability of incoming damage, a calculations of level of spike damage, and the healing fitting of the incoming damage, and much more.
    I would very much like to get some sort of feedback upon this, both on the mathematics, the interpretation of the models and the whether people are interested in this subject at all and want more.

    [edit: changed size of text to something more readably]

  2. #2
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    Unfortunately I'm not educated enough in mathematics to be able to validate your post, but I'd be very interested in seeing an easy-to-use tank/healer evaluation addon. It would help a lot in figuring out whether to keep a recruit or not during guild applicant trial runs.

  3. #3
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    If you think that tanking can be summed up in any formula you need to go back to tanking school. ........ more to respond when I have time

  4. #4
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    Math seems solid, but i really doubt it will have much practical use. More like something fun to know than anything you can actually use to down bosses. Cool project though.

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    Interesting ideas, but you assume that there is relevance on when between 2 swings of a boss a heal lands. This totally ignores the different healing styles as well as how different tanks work and puts Disc priests way ahead due to their absorbs.
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  6. #6
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    I think it can be useful when analyzing parses. We'll be able to see where mitigation/healing failed without an actual wipe or low tank HP.

    Might be interesting, but as the others said it will have limited use on it's own. It has to be used with other tools. I think the idea is too interesting to pass on.

  7. #7
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    I think you are omitting one important factor: LAG.

    The problem is that you will nowhere find what LAG a person had in each situation. It would be nice to have that and bring it in because it would actually tell you how reactive the tanks or healers are.

    Lets take a heal to bring my point accros: So you are a tankheal (in this case a holy paly), and the tank need a big heal like right now (at least you see it now). In your group you have a ret pally and a shaman ( so that you will be at 40% haste).
    The average reaction time is arroung 215 milliseconds (at least according to Human benchmarks: link ), your cust time will be 1,42 Seconds. So it will take +/- 1,635 seconds till the heal hits the tank (and that is only if we have a scenaryo without any LAG whatsoever, quite unrealistic).
    Lets add to this a LAG onf 100 milliseconds ( I would say that number is relatively realistic, its around where I am in Raid), so that would be then +/- 1,735 seconds till the tank gets the heal. If you have a boss that has a swingtimer of 2 secondsthat is quite a close call. And in this case its not even abour beeing a god healer or not. To prvent this probleme a healer would have to spam holy light.

    So in my opinion to make an apropriate evalutation you have to find a why to factor in lag.

  8. #8
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    Perhaps you could specify an average latency that gets factored into the calculation?

  9. #9
    Quote Originally Posted by Deathshay View Post
    Have you ever wondered how good performance a healer or tank are showing you? We all know that coming up with some simple form of evaluation of healers and tanks aren’t all that easy, especially since their group function is much more complicated than the simple: pull as much dps as possibly, without pulling aggro and doing it on wrong targets. But how do we come with some form of evaluation of tanks and healers? And is this important at all?

    So why would this be important, simply because evaluation is a powerful tool in testing setups (both gear, spec and group composition wise) and tactics, and will also serve as comparing between people for (pug) raid spots, so you have an idea whether you invited a overgeared fool or a undergeared top player.

    While I can see what you're trying to accomplish, it's a complete waste of time in my opinion.
    DPS is an easily quantified aspect of WoW. But for tanking & healing it comes down to one question -- Did it work?


    The trouble with both roles is a lot of intangibles or purely qualitative things, and when things don't go according to plan (and it certainly will at some point), these are the people that are going to have to step up their performance and at least try to pull things through. Does the tank know how to pull and position? Do they not just know to interrupt, but what to interrupt? How quickly do they react to a problem, are they aware of the full scope of the fight? And I've seen healers do things that don't seem to make sense while I've been tanking , and I've pulled some stuff out of my own ass that I don't fully understand myself. A combination of luck and playing smart I guess, possibly helping eachother out however we can like using cooldowns to help stretch a very finite mana supply.

    Experience is a very important aspect for both roles (moreso than the gear itself I'd say, though it's definitely needed to a degree), and it's nearly impossible to quantify that. Someone could be decked out in the absolute best tanking gear there is, but they got it through DPSing their way through it all and being given the items for their offset because the usual tank already has it all. And then they decide to field test it in a heroic only to prove they have absolutely no idea how to tank, all the while complaining that it's someone else's fault, thinking their gear is all they need. I've seen this exact senario several times, occasionally to the point I put on my own tank set (which is still of less quality of than the person who was supposed to be tanking) and do a far better job.


    Understandably people want to use simple numbers to evaluate people, especially when assembling a PuG raid.... but the simple fact of the matter is that you want your tanks and healers to know what the hell they're doing before you even consider the quality of their gear. They should also know the limits of their capabilities, as defined by what experience and gear they've acquired. You can't really carry a clueless tank, nor a clueless healer (as far as I understand it). Undergeared tanks and healers can be compensated for, but not ones who simply don't know how to do things. To make matters even worse, tanking is almost always self-taught. Mentored at best, but tanking itself is so full of intangibles that there is no real complete "guide" to teach you how it really works. You can be taught the theory behind it, told what the optimal rotations are like, and how gearing works.... but you'll never understand how tanking works until you just get in there and do it. Healers have their own lessons to learn presumably, as there are probably some triage decisions which have to be made.


    At best, you can hope to calculate these:

    How much EH is needed to survive a boss fight.
    How much EH and tank has based on their gear.
    How much HPS and burst healing is needed for a boss fight.
    How much HPS and burst healing a healer can put out based on their gear.

    Every one of these is a case by case basis, and none of them can answer the equally or more important question -- Is the tank/healer experienced & skill enough to do it?
    He who isn't afraid to stand by his ideals...
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  10. #10
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    Oooh. Great reply from Roht. So much here that I think should be brought forward and shared with others.......

    Quote Originally Posted by Loremaster Roht View Post
    While I can see what you're trying to accomplish, it's a complete waste of time in my opinion.
    DPS is an easily quantified aspect of WoW. But for tanking & healing it comes down to one question -- Did it work?
    Key idea. Did it work?. Was the result a wipe? No. Check. Did we beat the mob/boss? Yes. Check. Now, the varying degrees of which, that, is an entirely different matter. I do disagree that dps is an "easily quantified aspect". This is what I believe to be a "typical" statement from a tank or healer. Sure, you can assign a number to it. You did X damage over the fight. Nevermind any interrupts they may have thrown in to reduce incoming damage to the tank, or any loose mobs that they may have OT'ed back to the tank after ripping that mob off the healer. Nevermind the simple fact that the combined efforts of the dps may have shortened the fight to a point tolerable to the healer's or tank's ability to sustain a fight. Or, when stuff really goes sour and something does crumple the healer into a little ball of cloth, the ability of a dps role to quickly switch gears if possible, and pick up the healing job? The composite effect of the group cannot be dismissed out of hand, but the tank/healer combo is the core of that group.

    But that takes me back to one of my favorite sayings:

    The tank doesn't operate in a vacuum.

    Quote Originally Posted by Loremaster Roht View Post
    The trouble with both roles is a lot of intangibles or purely qualitative things, and when things don't go according to plan (and it certainly will at some point), these are the people that are going to have to step up their performance and at least try to pull things through. Does the tank know how to pull and position? Do they not just know to interrupt, but what to interrupt? How quickly do they react to a problem, are they aware of the full scope of the fight? And I've seen healers do things that don't seem to make sense while I've been tanking , and I've pulled some stuff out of my own ass that I don't fully understand myself. A combination of luck and playing smart I guess, possibly helping eachother out however we can like using cooldowns to help stretch a very finite mana supply.
    Again, it's how the group reacts when things get out of hand. The tank/healer combo does play a pivotal role though. I'm not going to beat on that dead horse any further. I do agree in many ways though. The tank/healer is the core of the group and are pivotal to the success of any group. They need to be able to step it up when need be, because if either falls, the difficulty level at best increases and depending on group composition, often preceeds a group wipe.

    Quote Originally Posted by Loremaster Roht View Post
    Experience is a very important aspect for both roles (moreso than the gear itself I'd say, though it's definitely needed to a degree), and it's nearly impossible to quantify that. Someone could be decked out in the absolute best tanking gear there is, but they got it through DPSing their way through it all and being given the items for their offset because the usual tank already has it all. And then they decide to field test it in a heroic only to prove they have absolutely no idea how to tank, all the while complaining that it's someone else's fault, thinking their gear is all they need. I've seen this exact senario several times, occasionally to the point I put on my own tank set (which is still of less quality of than the person who was supposed to be tanking) and do a far better job.
    The gear does not make the tank. The person behind the toon makes the tank. The gear will either help or hinder their success. Which leads us into.........

    Quote Originally Posted by Loremaster Roht View Post
    Understandably people want to use simple numbers to evaluate people, especially when assembling a PuG raid.... but the simple fact of the matter is that you want your tanks and healers to know what the hell they're doing before you even consider the quality of their gear. They should also know the limits of their capabilities, as defined by what experience and gear they've acquired. You can't really carry a clueless tank, nor a clueless healer (as far as I understand it). Undergeared tanks and healers can be compensated for, but not ones who simply don't know how to do things. To make matters even worse, tanking is almost always self-taught. Mentored at best, but tanking itself is so full of intangibles that there is no real complete "guide" to teach you how it really works. You can be taught the theory behind it, told what the optimal rotations are like, and how gearing works.... but you'll never understand how tanking works until you just get in there and do it. Healers have their own lessons to learn presumably, as there are probably some triage decisions which have to be made.
    Oh. You mean like "gear score"? The most abused "stat" out there?

    Tanking is almost always self-taught.
    Excellent point. Which brings to mind your previous example. With the person who had at least assembled some good tanking gear and made an attempt, do we take that person and steer them down a better road? Do we take the time to try and show them a better way? Or do we simply chastise them? I think a lot of it depends on the attitude. Are they receptive to criticism? Are they open to learning? It's very easy to pick on a tank or healer who is new to the role and developing their skills. It's very easy to dismiss them as "idiots" or "morons" without taking the time to help them gain the experience, or help them learn the role. How would you deal with a skilled tank who suddenly, in one particular encounter, struggles? Or a healer? Maybe all the way up to this point, they've been shit hot rockin' and rollin', but suddenly, faced with a particular encounter, just can't seem to pull it together? How are the two different?

    I'll be honest, I'm not one to tolerate certain types of bullshit. A new tank, learning, who starts off the instance and says "Hey, I'm learning, go easy on me," I cut the guy slack and watch to see what they're doing and try to help keep things in check if it gets ugly. The guy who comes in shooting off his mouth about how bad-ass he/she is, and then nosedives right into wipe or shows a profound skill for asshat-ery, I have very little love for. I also have little love for the tank.healer who think's they're too damn good for a group and bitches about "you're not doing enough dps". You know what? STFU. This is a learning opportunity for you, a chance to learn how to deal with a group that may not be up to snuff, cause there may be a time that you HAVE to tank against a boss or encounter where NO ONE is really well-geared. Oh wait, I forgot, everyone starts going into Icecrown Citadel with full tier 10 gear with gear scores of 2800+. Silly me.

    As for "optimal rotations", is there really such a thing? I think there are certain standard rotations that are good for "lead-off's", but as the old saying goes, "No plan survives contact with the enemy". What rotation is going to save your group's hide when an enemy rips off you and goes after the healer? A good tank needs to actually understand the tools at their disposal, not just understand certain rotations and gearing. The tank needs to be able to think and act and make "good" decisions in rapid manner.

    I think your final point hits the nail on the head though:

    Is the tank/healer experienced and/or skilled enough to do it?

    But again..... I fall back to my mantra........

    Tanks don't operate in a vacuum. They operate as part of a group.

    EDIT:
    Don't buy it? I'm going to give you two groups to tank for.

    Group A:
    Tank - Paladin
    DPS - Mage
    DPS - Warlock
    DPS - Hunter
    Heals - Priest

    Group B:
    Tank - Paladin
    DPS - Elemental Shaman
    DPS - Death Knight
    DPS - Warrior
    Heals - Paladin

    You're going to tank both the exact same way? Group A is pretty squishy. You don't have a lot of margin for error. You also have the fun of two potential loose cannons pulling trash you don't want (pets!). DPS for this group though should be through the roof. Group B, is a little bit more resilient and hey, even if the healer gets crushed, the shaman is likely carrying caster gear and can make a decent attempt to pick up the ball. And, in worse case scenario, you can always heal yourself. The other DPS are plate, so they're a little bit more resilient.

    Of course, all of this is dependent on the skill/experience/mentality of the rest of your group.
    Last edited by Leucifer; 03-08-2010 at 02:22 PM.

  11. #11
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    I'm majoring in physics and engineering and couldn't make heads or tails of the formulae. With healing, you can watch recount for heals per second and logs after an encounter. The only thing I can guarantee in a raid is that I will encounter Murphy's Law, something will inevitably go wrong and I will have to think on my feet (the healers will probably have to do some happy magic too.) The mathematics does not factor in tanks popping cooldowns smartly. Gear is just for show, sure it may get you better EH or healing ability, but experience will always be the main factor behind success.

  12. #12
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    Well when i look at a new tank, for guild requting i log the enconder, look at the moments where i know there is going to get a lot of damage around, does he use CDs there, potions what ?
    Else i look at position, can he do that right then he has tanked before, and depends on how he great he is doing etc.

    Dont think your formula will work, but as a programmer, i love to put numbers in order and solve the puzzle..

    as to Leucifers would i tank it the groups the same way, yes i would. As a paladin, druid, warrior tank i would.

    But think this is about raiding where you will have about ever class in the game. So there yes i would also tank the same way.

  13. #13
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    I've already played with this kind of things. I can join the chorus.... it's nice and fun and almost completely useless.
    I actually have some code around which takes a combat log and gives you a time/HP distribution and also computes the correlation function between the incoming damage and the incoming heals. I've used it to define a "reasonable" model of healing for a tanking simulator. You can also see the damage/heal delay for each healer (and easily see the difference between a hot-heavy druid and a reactive healer, healing for the first has a lot less correlation with the incoming damage). I've posted some graphs on emmerald.net and EJ in the druid tanking thread, if you are interested.

    The problem with all the math, is that you'll get nice lovely average values..... which represent nothing since a tank death (= often a wipe) is a single event, definitely not "average". So the important part of the distribution is the low-probability "tail" which leads to a tank death. This tail is not represented in the averaged values, but results more often than not from boss-specific events (forced movement, silence, etc), which can only be modeled per-fight (= it's a loooooot of work) and making enormous assumptions on the behaviour of the players.

    So I've switched to a practical rule: if at the end of the fight I'm alive and the boss is dead, then things were right. If it's the opposite, no

  14. #14
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    Quote Originally Posted by Mizariz View Post
    Well when i look at a new tank, for guild requting i log the enconder, look at the moments where i know there is going to get a lot of damage around, does he use CDs there, potions what ?
    Else i look at position, can he do that right then he has tanked before, and depends on how he great he is doing etc.

    Dont think your formula will work, but as a programmer, i love to put numbers in order and solve the puzzle..

    as to Leucifers would i tank it the groups the same way, yes i would. As a paladin, druid, warrior tank i would.

    But think this is about raiding where you will have about ever class in the game. So there yes i would also tank the same way.
    I think you'll maybe begin the approach the same, but take this into consideration:

    If the plate dps rips agg off you on a mob that you weren't presently targeting, how far does it travel?
    If the mage rips agg of that same mob, how far does it travel?

    With the plate... it's usually a simple matter of getting a good hit or two on that mob.
    With the mage... I'm having to use one of my other tools to do a ranged pull. It's also usually at the cost of a little more time and resources.

    But you're right, in raiding, very different. I was talking more along the lines of dungeons.

  15. #15
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    This is really a very long initial post about calculating the average (time-weighted) health percentage of the tank and its variance, both of which are much more straightforward than the post suggests (and most easily and trivially done by simply tracking the tank's health, without the introduction of damage/healing impulses). The result is also fairly useless beyond, yes, having your tank near full health most of the time is better on most fights than having your tank near-death.

    Furthermore, the variance gives you almost nothing. At best it gives you a rough idea of what an average hit looks like. A fight where the tank sits at 10% at the first half of the fight (without any change) and then 100% at the second half of the fight (again with no change) has the same variance (and mean) as a fight where the tank oscillates between 10% and 100% every second (as long as the total time spent in both is the same). The whole discussion about sigma distances incorrect and is a common statistical mistake - it -completely- depends on the distribution and only exactly applies for a normal (in the technical term, not as in 'standard') distribution.

  16. #16
    Join Date
    Dec 2007
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    A couple of questions:
    1. Are you sure you can get a large enough data set to make such an evaluation? I didn't see any discussion on the amount of data it takes to make sure those statistical calculations are sufficiently padded.

    2. On the initial equation: D(t)-H(t)=I*DeltaHp(t)
    a.) What is "I"?
    b.) Both D(t) and H(t) are discontinous. Having them equal the derivative of another equation seems odd as you cannot take the derivative of a discountinous function directly and having an equation whose derivative is always discontinous is hard to quantify since the results are random.
    c.) The units of H and D are both a health value while DeltaHp(T) is in units of "health per time". How does that work out?
    d.) are you considering edge cases? I don't see any boundary definitions related to the tanks max health or dying, which you might want to watch for incase.

    Anyways interesting article.

  17. #17
    Join Date
    Feb 2009
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    Quote Originally Posted by Noules View Post
    This is really a very long initial post about calculating the average (time-weighted) health percentage of the tank and its variance, both of which are much more straightforward than the post suggests (and most easily and trivially done by simply tracking the tank's health, without the introduction of damage/healing impulses).
    Actually, this is simple on paper. In reality it's impossible to reconstruct correctly the evolution of tank health during a fight due to lag. WoW tries to "fix" the lag (which is dependent on the various connections of different players) by allowing impossible situations to exist. If you process a combat log sequentially, looking at all the events which increase the health and decrease the health you'll end up with cases where the health is pushed beyond the maximum by heals which arrive BEFORE the damage they are supposed to heal. As a consequence a time-averaged value of health will likely be false.

  18. #18
    Join Date
    Sep 2009
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    DPS is science, Healing is Art, Tanking is Strategy.

    but also:
    I'm majoring in physics and engineering and couldn't make heads or tails of the formulae
    ^ This, I'm a EE currently taking a graduate level radar class (and am studying for that mid-term right now-ish) and the math for that is WAY easier than this, lol.
    "If the world is something you accept rather than interpret, then you're susceptible to the influence of charismatic idiots." -Neil deGrasee Tyson

    Twitter @Aggathon || @Tankspot || Twitch.Tv/Aggathon

  19. #19
    Join Date
    Aug 2007
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    Wouldn't it be a lot simpler to just put tank's hp, damage the tank is taking, and healing the tank gets on a time line graph type thing and look at the relations between the lines? What would this formula that doesn't make a whole lot of sense accomplish that that doesn't?

  20. #20
    Join Date
    Jun 2008
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    I like the idea of the thread but I do not see it working. Especially for the healing-part.

    There are at least two parts a healer has to excel. First he/she has to manage the normal/average situatione well. In normal situations it is ok (or sometimes important) to wait a little bit longer, manage mana or safe/brezz/buff someone else. Sometimes it may even be the right decision to dps a little bit.

    The other story is how one reacts in an o-shit-situation. That is around special encounter-wise attacs on the tank or the group and when the tank drops low or even dies. A good healer learns how to identify such a situation and how to react (or pre-act). Btw sometimes both tanks and healers cannot react with a CD at such situations because all CDs are needed for special attacs. So both have to react otherwise.

    A good healer is a healer who can do both. A healer who plays like there is an o-shit-situation all the time, will not last in fights where the whole raid is undergeared (like hard modes). It is important that a healer CAN switch between both modes at the right time.

    A third thing a healer has to be good as is: staying alife. There are situations where healers may sacrifice themselves for the greater good. Like standing in the voidzone to get the big heal to land on the tank when the boss has only 2% life. But most times healers should try to stay alife. And they should know how to do it without depending on someone else. Only a living healer can safe someone.


    But there is another problem I have with the calculations: You said that the tank (and healer) does not operate in vacuum. But you only look at tank-health. There are many encounters where the dmg on the group/raid is much more important than the dmg on the tank. Or where other people are focussed (by the boss and the healers). A good healer will at least help with the raid / group in such situations even if they are assigned to tank-heal. At least if the tank looks safe. They will not do much beside healing the tank but sometimes a single shield or heal or dispell may safe someone.

    BTW a good tank tries to help, too. He/she may pop a little CD to even the dmg on him/herself so the healers can concentrate on the raid/grp. Or may even help actively (dispell, slow, interrupt, intercept, ...)

    I do not think that is coverd with the math. A better approach would be to break the data down into segments: normal segments, tank-endangerd situations, healer-endangerd situations and raid-endangerd situations. Maybe you can do that semi-automatic. Like finding HP-spikes (in each direction) to everybody and looking for special abilities (silence, dots, etc). It would be a good idea to eveluate the segments seperatley. With different metrics.

    If that would work (I'm not sure if it is doable) you could get information like:
    - The tank knows the basic moves and does not let any buff / debuff drop
    - The tank knows how to react in special situations
    - The tank reacts to stuff happening to other persons
    - The tank taunts on rdm times
    - The tank taunts if someone is focused who should not be focused
    - The usage of taunt implies that the tank knows the encounters

    - The healer stays on the tank all the time
    - The healer helps the tank in special situations
    - The healer concentrates on the raid in situations where the tank is endangered (someone should stay on the raid!)
    - The healer knows how to heal a raid/grp if there ist heavy raid/grp-dmg
    - The healer never used CDs
    - The healer used CDs every time they were free
    - The healer tried to safe X people
    - The healer gets too much dmg

    A combination of such informations would be much more helpfull than any bunch of average numbers.

    To evaluate someone, you have to compare if the usage of buttons is appropriate to the situations. As you said - if the health-bar of the tank is spiky that may indicate totally different things (he has so much EH that the healers don't have to worry so much or he has nearly no EH). We cannot get much more information from the average numbers of the health-bar. One has to focus on special situations. The same thing one does when we evaluate performance while looking at a parse.

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