Drop Theory Experiment

OK. I should be able to get online sometime around 7:30; I'm meeting some other friends around 8pm, but that should be enough time.

Feel free to send a PM with your in-game name (since it can't be Sentinel

^^^^^

This is wrong, it shouldn't be X1-X2 but (X1+X2)/2, i.e. the sample mean. Assuming your calculations for the interval are right (my memory of confidence intervals are pretty much gone, so I googled the term and found no formula matching your own, but whatever), you get an interval of confidence of:

0.625 +/- 0.27... or 0.355 < x < 0.895

Which would tend to indicate that the gathered sample does not, in fact, hint at a non normal distribution.

The sample size was not 40 but 20 (i.e. 20 battles total). From this site:

So not necessarily.

Not in this case, apparently.

The theory of drops has always intrigued me - it would be better if ANet would simply tell us =P

A few other things I would like to note:

Concerning chests, I think the person that opens it have a higher chance of getting an item from the chest. That, or the theory of proximity comes into play here. For me, it always seems that the person that opens the chest gets at least one item - but I am always open to the theory of complete randomness, since its hard to rule that out.

An example is the first quest in FoW, the clearing of the tower by beating that Shadow Beast. After killing it, a chest appears, usually with purple armor of some type.

The other strange thing about drops, is that there is a certain theme that may exist. On some runs, you might get a string of bows, or you will get a ton of blue items that have similar mods or wands that have similar elemental properties. Again, I won't rule out the existence of 'coincidence'.

This 'theory' is more prevalent on runs of FoW. Two of the main item drops there: the Chaos axe and Shadow Shields. On one run, I may get 5-6 Chaos axes! Same with shields. And my party member will get none. On other runs, I may not even get one Chaos Axe/SSheilds, when a party member gets a string of them.

Then comes the factor of enemies stop dropping loot, which Anet seemingly introduced a few updates ago (June 15th I believe).



Although they say this only happen when you "rejoin the current map". It would be terrible to find out that the 'game' sees you as doing FoW ventures over and over, and therefore stops you from getting more Chaos Axes and other special items.

You would be correct, however I'm not trying to calculate a mean there with X1-X2, rather I'm testing that the difference between two means is zero. Hence they should not be divided by two, I want the ACTUAL difference, not half the difference. Sorry, I may be wrong about some of what I posted, but that's not it

Again, I'm not averaging the means here. You average the means when you're trying to use repeated sampling as your technique. In this case, I'm testing the difference between means. The sample size is indeed 40.

Thanks for the attitude. I don't mind being wrong but when you fail to read my post and then give me attitude I don't think it's terribly good form.

-Diomedes

For the record here, you just made things much worse for yourself. Since I'm taking the difference between means, if there was NO difference, then zero would be inside the 95 % confidence interval. Mine came close to zero, but yours just got much further from zero. I think the key here is that you haven't read my post carefully enough to see what I'm trying to calculate. Instead, as you said, you typed, "confidence interval" into google. Sorry, sometimes understanding math takes more than a google search.

-Diomedes

Just to throw my experience in, I do solo tanking for 5/6man Underworld smite groups on most nights if we have favor. Usually the casters are just on the edge of my aggro range while the mobs are surrounding me. It seems like my item drops are about evenly distributed at 1/5 or 1/6 share, maybe slightly less. Sometimes I do some minor smiting, but not quite the damage that the ele nukers are doing. Sometimes I don't smite and just concentrate on tanking.

This leads me to believe that drops are mostly random and maybe slightly damage based, although not much if at all.

I would have done a simple Chi Square.

_________Far_____Near____Total
Dropped___8_______17______25
No Drop___12______3_______15
Total _____20______20______40

while expected would be:
_________Far_____Near____Total
Dropped__12.5____12.5_____25
No Drop___7.5_____7.5_____15
Total______20_____20______40

So:

Chi^2 = (17-12.5)^2/12.5 + (8-12.5)^2/12.5 + (3-7.5)^2/7.5 + (12-7.5)^2/7.5

thus Chi^2 = 8.64, df=1

Making it significant at alpha<0.005

In other words, if the drops aren't affected by proximity, the chance of getting the drops recorded randomly is < 0.005, or less than one in 200. The only assumption that the chi-square test makes is that these trials are independent. However, givin that the same spells weren't used and such, and that there are tons of other factors involved (how the presence of your character closer to the target affects the damage distribution on other players, how you affect their ability to do damage, where you employed more single/aoEspells, total damage attributed to you and to other players...) I'd say it's tough to come to a real conclusion, though there is no doubt that whatever happened between those two situations, some factor or combination of factors, including change in proximity, caused there to be a change in drops.

You failed to mention one key factor: the value of each item dropped. I'd gladly take 8 good drops to 17 junky drops...

No. I assumed you were computing your interval right but had made some mistake when computing what I assumed you wanted to be the mean. My formulation implied that both assumed populations where compatible with a normal distribution according to the traditional use of intervals of confidence. Since this isn't the case and I don't care enough to calculate the interval (I play a warrior, hehe), disregard my post.

Sometimes, but very rarely. This basic high-school statistics stuff doesn't. I'll preempt any insinuations on my mathematical background by noting that I'm a grad student in image processing, so, yeah, it's been a while since I made use of stats exensively (Bayes Theorem excepted), but any misunderstanding on my part definitely stems not from my own inability but rather from a lack of clarity in your presentation, IMO.

"You failed to mention one key factor: the value of each item dropped. I'd gladly take 8 good drops to 17 junky drops..."

How does this matter? If drop system is random, then it doesn't mean "less items = better items". Personally, I don't believe half of these "theories". As a Monk, I might sometimes *not* heal at all, if the battle is easy, and I still get the drop. Only this that is *certainly* true, is that if you're too far away, you will not get the drop.

.. I was under the impression that code couldn't account for a true random--and, in fact, that there has to be a degree of 'method' to it.

Just use Chi-square. It's very good with problems like this, as it has very easy to interpret results - it simply says that the two (or more) conditions aren't independent - that is, there exist factors associated with being close or far that changes the number of drops. The assumption is simply that there isn't such a difference, and alpha<0.005 is 10 times the alpha needed for publication in most journals.

Well, in this type of situation the difference is academic. It wouldn't have any effect - it's like claiming that die rolls aren't truly random because the thrower will tend to release the die on similar angles, and that the facing of the die pre-launch on a given throw will influence the next throw - possibly, but it is a minute effect if any. It only really matters when you are having issues with picking seeds - the actual numbers are generated by a formula, and if you know the seed and the formula used you could predict the rolls, hence they aren't random, but since it isn't the "randomness" that's important, but that it distributes things with equal odds in non-visible patterns it isn't really a problem.

Chi-square... I have vague memories of sleeping through that. No, I saw your post on page 2, and, yeah, I guess it would appear from this (albeit limited) sample that drops aren't completely random. I'll drop by again to see what tonight's experiment finds out.

what is defined as far distance?

being within spell casting range of killing things? ie within danger circle?



only asking because I want to do same test using only 2 players

- I have 2 computers, 2 accts

Diomedes,

Define near(N) and far(F)...lol....and how in the world you know what the frequency for N and F are. Are those numbers (.85 and .4) assumptions?? Or you know them for a fact.

Because, if they are guesstimates..well..I need to say no more...:-)


JoDaimonds,

<-----ING (the W one)

Sent.-

He's using the figures provided by Uldrath in the original post.

I know then since the OP posted them, go back and read his post, then my post, it'll make more sense. I was going to use N and F from then on as subscripts but I can't do that given the tools available to me on this forum.


-Diomedes

I'm fine with using Chi^2, I used the other method since I figured it'd be more intuitive to follow. Given the reaction that I got however, perhaps your way is far better (it's at least, a lot easier to calculate). However I agree with what you've posted, there are other factors that probably need to be accounted for. I'll try to repeat the experiment farming flesh golems with two people. I've noticed that you can stick one person up front for all the enemies to group around and have the second person cast AoEs fairly easily. As the groups of flesh golems are fairly constant, I think this experiment can be done by entering and exiting the area repeatedly and just killing the same first two groups over and over.

I'm sure that if there is a drop formula, it does probably involve more than just distance, but I think a person can make a good attempt to remove the other factors.


-Diomedes

It has to involve more than distance, otherwise warriors would get far more drops than anyone else (except possibly the odd caster "tank", hehe), assuming the warriors do their job and shield the casters from the brunt of the mobs. This hasn't been my experience, i.e. I never noticed any bias in my favor when it came to drops.

theres 3 different distances to take into account


- melee distance

- spell casting distance, which is the same as danger circle

- peripheral distance
(only rangers and healers can be outside the monsters danger circle and yet still affect combat)

OP, your experiments are null in void because you did not count drops when there are creatures in less than groups of three. This will thus skew the odds because you may have gotten a drop off of one of these creatures... but your results are still nevertheless interesting and should be taken into consideration for further testing.

or maybe quality of the drops plays a role too? for example,

playerA got: junk, junk, junk, junk

playerB got: junk, rare item, junk

next item dropped is a rare item, then it'll be reservered for playerA even thought A got more loot count already?

maybe the game keeps loot count table like,
playerA junk loot count: 4
playerB junk loot count: 2

playerA good loot count: 0
playerB good loot count: 1

so now if a junk loot drops, it goes to B. next junk item would go to B again because B would be still behind on junk loot count.
if a good loot drops, it goes to A.

so pure item count may not tell the whole story.

Also, the OP failed to mention the totol item drops. If in ranged fight test, 16 items dropped totally, then OP got 8/16. If in closed range fight, 35 items dropped totally then OP got 17/35, then it's worse than ranged fight.

too many unknowns in this test to draw any conclusions.

Anyone that's trying to experiment on this needs to remembers about the "kill lists" or entering and exiting the same area when counting drops. If your running it with the same people over and over again, you should be fine because the drop rates should remain the same. However, if you do it with different people then your results might be skewed.

Also the people participating in the experiment should also probally go run a mission together or something else first for the same reasons (e.g. One person has farmed flesh golems and a second hasn't, the first persons drops might be reduced if you run the experiment on flesh golems).

I was only planning on doing Mission 1: North Wall for my test

- anyone post searing can validate the same test

This is true to a misleading extent. There are always code tricks used to simulate random numbers, but that is deeply hidden for most purposes. Programmers definitely do things like:

"Generate a random number from 1-8. Give the item to that player."

They don't have to do anything more complicated than that (thought they might well do so).

Guys,

Let's think about this from a programmer's stand point.
You need to write code that assigns loot to players on a MM game.

The smart programmer will write something simple that runs fast and takes as
little memory as possible. All these things that you guys say about keeping track of this and keeping track of that and then calculate this based on that take up memory and require more processing power.
Think about it...this game is played by thousants of people that create hundreds of instances every few minutes.
To keep track of all of these things, as some of you are suggesting, you better have supercomputers as your servers and then some. I may underestimate the computing power these days but I know one thing. The simple code is the best code.

So what do i think is happening??
Simple:

Each map has a specific number and type of monsters.
You never saw a map with different or less creatures in it, right?

On every instance of this map, loot is assigned immediatly to each creature
and the only rule on that is that loot can not be inapropriate for the type of monster. For example devourers can not be assigned minotaur horns or this sort of thing. This may be more complex as from my experience bosses get better loot....sometimes.....Also different maps have different sets of loots
You don't see Chaos axes in presearing ascalon, do you?

Moving on:

So a group of, say, 8 players gets into the map. The map gets intitialized as above, an invisible 8 sided die is spawned and the killing begins. Each player is assigned a number from 1-8, propably depending on their place in the group listing.

The first monster is killed, the die is rolled, and the previously assigned loot goes to the player with the lucky number.

Second monster is killed, the die is rolled again and this monster's loot goes to
the lucky number.

The process is repeated for each monster killed.

Simple to code, nothing to track down, easy on the old proccesor and fair because it's RANDOM.

Now everyone that has ever rolled a die knows that sometimes it's hard to roll the number you want and sometimes you get it all the time. Same here. But here the unlucky "feeling" that players get is compounded by the fact that sometimes when their number comes they get the monster with the crappy loot. Add to that that everyone likes a good conspiracy theory and you end up having a thread like this one

We are going to be running our own experiment with JoDiamonts. Go in a map and while he stays at the spawn, I'll go deep into the map and kill 20-30 nasties. According to some theories he will get nothing or close to nothing. I say, if we do it enough times he will get exactly 50% of the loot which will piss me off, but what can you do...lol
Will report back nomatter what the result.

Sent.-

It would be simple, but it clearly doesn't happen that way. That's what statistics are for, determining if the loot distribution is random or not. It clearly is noot the same in the two instances, or if it is he had an odd (1 in 200 or more) run on which he measured.

I suspect that if you park a guy and run off killing stuff you'll get all the drops and he'll get none, once you reach some threshold distance.

Ive already seen this, as have other people

after a certain amount of distance
- you get zero loot if too far away

not some --- its zero



but thats alot different than this other hypothesis that arguing for a weighted distribution


loot is random, doesnt matter where you are in the danger circle
(melee or spell casting)

Let's keep this factual, instead of spouting opinions. Statistics will answer that question if people record observations. I have the distinct impression that I get more drops the more damage/healing I do, but I will wait till I gather data - if you truly feel it is random that's fine, but unless substantiated it is an opinion, and I believe we are looking for facts.

I'm sorry but you can't draw any conclusions on the OP's experiment. He says he recorded battles of groups of more than 3. That right there throws his experiment out the window.
He should have recorded the number of enemies killed, not groups. We will never know how many groups of 3 he faced and got something the first time and vise versa.
The only way to run an experiement like this is to count enemies.


Ninna,

I never noticed this but then, i was never looking for it either.
I will know soon enough too. Any idea how far is far. I have a couple of spots where we can vary his distance and see if that will change anything.

Sent.-

ive tested this too

goto Mission 1: North Wall


- leave one person at entrance

- kill stuff on the map, kill the named, open the lever to open the door to the next area
(where the bonus and gargoyles and other stuff is)


thats a large enough distance where you will see zero drops for the person back at beginning of mission

but its a BIG distance before this happens
- you dont have the party anywhere near on your radar
- you are probably at least 500 feet away

True - I had assumed the numbers were probably similar, as often enemies in an area will occur in standard groups of 4 for example. A precise number is required, but even tweaking the numbers a little won't affect that chi-square much - it's a pretty high chi-square value, and unless when he was arther back the groups were 1/2 the size I don't think it'd make a difference. I suspect he's right and that there was a difference in drops caused by some factor (amount of damage he received, proximity to targets, amount of damage dealt, combination of these (for example - proximity develops "hate", as does damage - perhaps some combination of proximity and damage then could account for drops, in terms of a developed "hate" for the player.)

I can personally say it is random loot. I play with the same 2 people every single time I play. Me a War then a Necro then a Monk.. There we have close middle and far range players.. We usually take the henchies to fill the group. I open all the chests and I do not always get loot. We 3 have all gotten the same amount of loot quality and quantity.. I know this because we are all in the same room as we play and we share loot..

Granted no hard tests or anything but if I the warrior was getting more loot because of proximity then we would have noticed it. btw we have been playin since late may.

No offense...but that's crazy talk. If the programmers want to do some complex calculation for loot drops, the processing power and memory of holding these simple variables and doing a bunch of arithmetic is the last thing on their minds. We aren't programming in the 80's fer chrissake. I mean come on, just look at how unnecessarily complex the damage calculations are, and damage is something that is applied several times more often than loot drop calculations.

I know you think that instancing the game hundreds or thousands of times changes that, but it doesn't. Even within a single instance, the fraction of the total amount of computation being done that is taken up by loot division is insignificant compared to all the other things the server already has to handle.

same

Ive 2boxed 2 characters at the same time for mission one

my level 20 does all the work clearing the stuff
the 2nd level 6 character tags along in "experience" range


you can call it a bot but im working 2 keyboards at the same time

my leech newbie alt gets half the drops without doing anything but autofollow

exactly what I think

Actually many Ele spells have a range greater than the aggro circle: You can move up to a mob and cast most spells from outside the circle (the mobs will not react to your presence until your spell goes off).

I regularly let the W go aggro the group while I stay WAY back and once he has their attention I start casting my AOE, letting the game move my toon close enough to cast, which always leaves me just outside the aggro circle. Very evident when fightin giants, as their giant stomp knocks down anyone inside the aggro circle, yet I don't get knocked down from my casting location.

I *have* noticed that you need to be very close to the aggro range to be in the running to get a drop if you haven't contributed to the battle in some way. This is evidenced by the fact that if I stay a slight distance (like a distance = 1.5 * radius of the aggro circle) from a mob and don't contribute to the fight, I will not get any XP for the kill (and no drop either).

As far as the OP, I cannot say I have any useful evidence one way or the other.

I will say we went to FoW last night and 5 Obsidian Shards dropped early on. I as an ele got none. One person got 2 (one of the warriors) and 3 others got 1 each. Not a statistically valid sample but it sure irked me. All I ever get in FoW is alot of whites and a few blues and the very rare purple. I never get any of these interesting drops like chaos axes or eternal weapons or rare materials.

There also must be some sort of 'loot meter' that everyone has. Since killing a type of enemy over and over will make them run low on loot, I wonder if you joined with a group and went and killed the same type of enemy, if your 'loot meter' would still be low or reset itself.

For instance if I went on solo drake runs 5 times, and on the 6th I joined a group and we went killing drakes, if my loot meter would still be empty. I have the belief that once you enter a map, the drops are set in stone. Not totally set were you can predict, it's still a roll of the dice.

For instance, I saw a Shadow Monk in FoW holding a Chakram (those circular metal things). If you were to kill him, there would be a 'chance' to get that chakram (rare or not). The roll of the dice part is that he could drop dark remains instead, or whatever shadow monks drop, or even gold, which is for the entire party. I've seen a ranger in Riverside Providence, and when he hit me with his arrow, it said on the screen 'Life Stealing", which means if I killed him, there is a possibility of him dropping that vampiric bow, or possibly even nothing at all, if the game deems that I killed too many 'rangers'.

I'm getting a little off-track here, but I think two factors to consider: once you spawn a map, certain items may be included in a roll that could drop. Ill take Lightning Drakes for an example, although this might be a bad example because they don't 'carry' anything visable (like a s. monk carrying chakram)


(assuming you solo)
gold
spiked crest
scales
rare item
.... etc (weap, shield, foci, whatever)

take into account your loot meter, if you killed an enemy too many times the % of getting rare item would drop. I know this topic is mainly on "who" gets the drop, but I thought I would point out this other factor we might consider for discussion

Add to the fact if you went with a group instead, your rate of rares would definitely drop, actually your drop rate overall would drop. I'll let you guys determine what factors determine who a drop, randomness or some other ...

i got a e/mo lvl20 and one Me/W still in old ascalon. the mesmer already had three times the dye drop before him than the elementarist.

Sentinel and I tested some theories today.

We went outside of Augury Rock. I sat down. Sentinel went far, far away and killed a bunch of guys.

Drops: 11 for Sentinel. 0 for JoDiamonds.

Then we did the Elona Mission. I stayed well outside his danger circle, but kept him in my minimap (and close enough to be selected, also; if you get too far away you lose selection). We did this twice to kill enough enemies.

Drops: 7 for Sentinel, 6 for JoDiamonds

Each time, I made sure to not cast anything or pretty much do anything at all.

Likely Conclusion: Dealing damage or healing or doing anything at all doesn't matter at all; it only matters that you are close to the monster when the monster dies. "Close" means "shows up on the minimap", or maybe just that you can select the monster.

Possibly, you need to be close enough to the killer, which could be much farther away if the killer is using ranged attacks. That warrants a little more testing, maybe.