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Is my opponent just luckier than me?

 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 23, 2008 4:32 pm 
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As part of my PhD, I'm taking a statistics class, and for this class I need to complete a project that needs to be done quickly from experimental design through data collection and analysis. This needs to be a new study, and cannot have anything to do with my research. So for my project I decided to do something related to 40K.

I've a friend of mine who I play regularly against, usually 40K. And we've always joked that somehow he seems to have trademark good luck (particularly with his Eldar) while I typically show appalling luck. So I decided to test it.

For those interested in the stats, the design is a fully crossed 3-Factor ANOVA. One factor is the player (me and my opponent), another is the dice roll needed (3+, 4+ or 5+ ... other rolls [2+ and 6+] crop up too infrequently to be useful and contested rolls, difficult terrain rolls and leadership tests also don't fit the analysis). The third factor is importance of the dice rolls (high or low, agreed upon by both players at the time of the roll).

As for armies (from memory) - 500 points
My opponent:
Eldar
Autarch (Warp-jump pack, fusion pistol and lots of power weapon attacks)
10 Striking Scorpions (Exarch, power claw, infiltrate & move through cover)
10 Dire Avengers (Exarch, shimmer shield, defend & bladestorm)
10 Dire Avengers (Exarch, shimmer shield, defend & bladestorm)

Me:
Chaos Space Marines
Sorcerer (doombolt, Mark of Slaanesh)
6 Noise Marines (sonic blasters, blastmaster)
6 Noise Marines (sonic blasters)
6 Lesser Daemons

We played 8 games total (multiple games required as replicates - hence the small points size) on a 4x4 board with about 25-30% terrain. Every 3+, 4+ and 5+ roll recorded. Note that the actual outcome of the game is not a factor in the analysis (just how good the dice rolls are), but has been included for your interest.

Game 1: Cleanse
Eldar win, absolute miserable slaughter. None of his units under 1/2 strength.

Game 2: Take & Hold
Edar win, much closer game. Scorpions & autarch dead, handful of avengers survive due to lousy saving throws on my part and the fact that distract makes them such a damn tarpit in combat.

Game 3: Loot
Eldar slaughter (again). Bladestorm is a bitch. Lost an entire squad of marines to one salvo.

Game 4: Annihilation
Eldar eliminate all Chaos forces (seeing a pattern?). Put up a bit of a struggle this game, killing the autarch and reducing all of his squads below half strength.

Game 5: Recon.
Eldar slaughter all Chaos forces.

Game 6: Annihilation
Yep, eldar kill all chaos forces again. Highlight of the game was my sorcerer charging a squad of Dire Avengers (clipping them, only 3 in the kill zone) and being killed outright (see what I mean about my trademark luck?). By this stage I was getting a bit knarly about this, and checked his list as he just seemed to be having his cake and eating it. Yep, about 100 points over. He drops the warp pack and I added in another squad of daemons to compensate.

Game 7: cleanse
Chaos win! Only one squad of daemons and one squad of noise marines left. But all Eldar dead!

Game 8: by this stage we really didn't care too much. I think it was loot again.
Eldar win, but only a handful of Eldar left.

So, 7-1 to the Eldar, but fortunes for the Eldar changed in the last two games when actually forced to engage in a fair fight!  Damn those sneaky Eldar...

Now... what's the results of the analysis? My opponent did, indeed, score significantly higher on his dice rolls than me (p=0.001)! Not only that, but he scored significantly better than me when the rolls were important (regardless of what he needed to score).

So there you go. Perfectly justified in claiming that my lousy win record is due to my opponent being luckier than me!  (Or maybe I need to have a look at his dice? )

Here are my theories to explain this - this is a freakish result, way beyond anything I would have expected (any other theories welcome - I can use it for my write-up!)

Pure random chance
It's possible there is no pattern and these things have simply cropped up by chance. Well, the analysis has calculated this probability - there is a one in a thousand chance of that. That's a very low chance (well within what's scientifically acceptable as non-random) and completely not what I was expecting! Not only that, but the reason for the study in the first place was anecdotal suggestion that he rolls better than me.

Loaded dice
Not necessarily loaded, but quite possibly uneven in some way. While differences in dice might explain the differences between us, it doesn't explain why he rolls better for important dice rolls.

One possible explanation would be that he has certain "lucky" dice. For regular rolls, he just grabs any old dice. For important rolls he (conciously or unconciously) may prefer to use certain dice. This may not even have anything to do with favourite dice - for example, if his 3 blue dice roll better, if he uses them to distinguish his power weapon attacks, he's consistently going to be using them for important rolls.

Still, there are some dice rolls like scatter dice where we do use the same single dice and he does seem to do better for them. And it doesn't explain Ld tests which require low rolls! Out of those 8 games, he made somewhere between 3-6 leadership tests (morale or pinning) per game. Not one single failure. Unfortunately I didn't record how many exactly, or I could run the numbers on that too...

Rolling technique
I seriously doubt he has a magic technique he's not telling me about, but most wargamers have stupid supersitions about the dice. For example, I tend not to roll dice that have rolled well again - I pick up new dice. Probably stupid, but it is possible something like this could be affecting the dice roll - particularly if there is some non-random likelihood of getting a given roll dependent on the type of dice being rolled.


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 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 23, 2008 4:43 pm 
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This needs to be a new study, and cannot have anything to do with my research.


Gak!  That just about sucks.  I've not had a class yet where the professor intentionally steered anyone away from something with thesis/dissertation applicability.

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 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 23, 2008 4:44 pm 
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(Lord Inquisitor @ Apr. 23 2008,16:32)
QUOTE
My opponent did, indeed, score significantly higher on his dice rolls than me (p=0.001)! Not only that, but he scored significantly better than me when the rolls were important (regardless of what he needed to score).

Wow. That is significant. However, I doubt that most statistitians would be happy with n=8.  :D

There is also an issue with exactly how many dice rolls are required. If you are a player with a horde army who - for one reason or another - makes more dice rolls, the results will even out better.

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 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 23, 2008 5:28 pm 
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I don't have statistics to back it up, but Dave is definitely luckier than I am when it comes to rolling for CC resolution. I swear that half the time he rolls a 6, which is especially infuriating when I have something like +7 and he's +4 and he ends up winning the CC.

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 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 23, 2008 6:51 pm 
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(nealhunt @ Apr. 23 2008,11:43)
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Gak! ?That just about sucks. ?I've not had a class yet where the professor intentionally steered anyone away from something with thesis/dissertation applicability.

Well, it makes sense in this case. He wants it to be quick, easy and non-technical so that we can all understand the process of experimental design. If we have pre-existing data or experiments then we might side-step it. It's actually been one of the most useful exercises I've had to do, so I don't begrudge it.

There are other things that are downright wierd. For example, for the candidacy exam, I can choose written exams or write a grant proposal ... but the grand proposal can't be for the project you are going to do for the PhD (although it can be related)... which makes no sense to me - a grant proposal on what you are going to be working on - that would be something really useful!

Wow. That is significant. However, I doubt that most statistitians would be happy with n=8. ?:D

No, that sample size is just fine. I did power calculations beforehand. The ANOVA takes the sample size into account, so if you get a significant result, the sample size was big enough!

It might be a little bit of an issue for those tests that didn't turn out to be significant, but since the only ones that I was interested in (me vs. him and the interaction with importance) all came out significant, it isn't going to change my caculations. I will be calculating power values anyway for the analysis, which I can post if you're really interested...   :;):  

There is also an issue with exactly how many dice rolls are required. If you are a player with a horde army who - for one reason or another - makes more dice rolls, the results will even out better.
That's not a major issue - I designed the study that the replication was equal. A single replicate would be the proportion of, say, 3+ rolls of high importance for a single game. Exactly how many actual rolls represents only how much subsampling within each replicate - yes, the ones with low subsampling showed higher variance. But even if there were insufficient subsampling, it would increase variance, which would obscure an effect, not create one (essentially, it would underestimate any effect, not overestimate). He did roll slightly more dice than me overall, but that just strengthens the conclusion. I'm going to do a secondary analysis and look at how much we deviated from the expected norm and he deviated from expected more than me.

Not only that, but the data is normalised against the expected distribution, meaning that the 3+, 4+ and 5+ can be compared - and there was no overall significance difference between needing a 3+, 4+ or 5+ if you don't consider any other factor. So I am sure this isn't a problem.

I don't have statistics to back it up, but Dave is definitely luckier than I am when it comes to rolling for CC resolution. I swear that half the time he rolls a 6, which is especially infuriating when I have something like +7 and he's +4 and he ends up winning the CC.
You should start recording it. Just keep a note every time of both rolls and per game. Once you've got a fair number, you can eyeball it and see if you're right or even run some stats on it. It's damn interesting!

I know my opponent is not going to be allowed to forget that he's a statistically significantly lucky git! ?:laugh:






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 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 23, 2008 8:35 pm 
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Ah but when you are losing its is a snowball effect. So a bad roll 'costs' you a lot more and wieghts your rolls in future more.

I find in Epic 1st turn bad luck is far worse than 4th turn bad luck, and after having 1st turn bad luck every roll is that much more vital.

Maybe dice feel pressure? :)

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 Post subject: Is my opponent just luckier than me?
PostPosted: Mon Apr 28, 2008 9:32 pm 
So, what will your follow-up experiments be? Something to remove the rolling technique variable, such as a dice tower? Or mark the dice and use the same consistently?


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 Post subject: Is my opponent just luckier than me?
PostPosted: Tue Apr 29, 2008 2:26 am 
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Several quick thoughts here.

1) Lanchester Theorem
(This is a complex way of agreeing with TRC). Basically the side with a small size advantage in tends to destroy the inferior force for limited losses where there are a number of consequetive engagements. So assuming 50:50 results in even combats at 66:33 results in 2:1 combats, this has the following kind of results

Round #1 "Red Force" 50 planes Vs "Blue force" 40 planes,
? ? ? ? ? ? Red losses 18, Blue losses 22

Round #2 ? ? Red ?32 vs ?Blue 18
? ? ? ? ? ? Red losses 6, Blue losses 12

Round #3 ? ? Red ?26 Vs Blue 6 - anahilation

============================
2)  Were you using the same dice??
I am told that round corner dice ?apparently work differently from "sharp" cornered dice. It seems "Round" dice may be easier to control and so less random

============================
3) Were you using a shaker and a regular point to throw the dice?? If you consider 'Craps" ?(or any other dice game for that matter), you will see that there are a number of requirements imposed on the players to try to make the rolls as random as possible - like they must hit the vertical wall at the end etc ?

============================
4) Relative importance of the throw
As others point out, events in the game may reduce the number of dice thrown by one side or the other. So if you get a significant number of failed activations, this will restrict the number of other dice thrown, and also make their results more significant as well - both of which will tend to skew the results.

Combined with the "Lanchester theorem" above, this goes on to suggest that EPIC is really about reducing the number of dice thrown by your opponent (so you try to reduce his activations by loading BMs and breaking his formations etc). The side with the greates number of dice in the game is the one that will usually win.

But is that something that can be proved??

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 Post subject: Is my opponent just luckier than me?
PostPosted: Tue Apr 29, 2008 2:42 pm 
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(Ginger @ Apr. 28 2008,21:26)
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It seems "Round" dice may be easier to control and so less random

Really? I would have thought the opposite would be true. I've noticed that rounded dice tend to roll a lot more, sometimes annoyingly so, than squared dice.

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 Post subject: Is my opponent just luckier than me?
PostPosted: Tue Apr 29, 2008 2:45 pm 
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Really? I would have thought the opposite would be true. I've noticed that rounded dice tend to roll a lot more, sometimes annoyingly so, than squared dice.


It is notable that Casino dice (Reputed to be the most reliable) are square-edged.

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 Post subject: Is my opponent just luckier than me?
PostPosted: Tue Apr 29, 2008 3:46 pm 
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(Ginger @ Apr. 28 2008,21:26)
QUOTE
Several quick thoughts here.

1) Lanchester Theorem
(This is a complex way of agreeing with TRC). Basically the side with a small size advantage in tends to destroy the inferior force for limited losses where there are a number of consequetive engagements. So assuming 50:50 results in even combats at 66:33 results in 2:1 combats, this has the following kind of results

Round #1 "Red Force" 50 planes Vs "Blue force" 40 planes,
? ? ? ? ? ? Red losses 18, Blue losses 22

Round #2 ? ? Red ?32 vs ?Blue 18
? ? ? ? ? ? Red losses 6, Blue losses 12

Round #3 ? ? Red ?26 Vs Blue 6 - anahilation

None of this really affects the issue at hand - whether he won or not, we were just looking at the distribution of the number of successes.

Yes, he rolled more dice, but surely you'd think that would simply make him, over the course of the 1,800-odd dice he rolled, to match close to the expected distributions?

Here's a graph of the actual values:



Blue is me, red is him. Light colours are low importance, dark are high importance.


============================
2) ?Were you using the same dice??
I am told that round corner dice ?apparently work differently from "sharp" cornered dice. It seems "Round" dice may be easier to control and so less random

No, we certainly were not using the same dice and I would suspect we can lie the root of this discrepancy at the dice in some way.

Indeed, my dice are uniform, small round-edged dice similar to GW dice (but pink and black...) His are large, and there are a mixture of dice in there, but many are sharp-edged.

Basically, I wanted to simulate normal playing environment - maybe if we use the same dice, a cup and a box to throw into then this will go away - but that's not what I wanted to test! I wanted to see what was happening during our normal games.

============================
3) Were you using a shaker and a regular point to throw the dice?? If you consider 'Craps" ?(or any other dice game for that matter), you will see that there are a number of requirements imposed on the players to try to make the rolls as random as possible - like they must hit the vertical wall at the end etc ?
Again, no - I wasn't interested in controlling for every variable - I just wanted to see what our normal play resulted in. Although I might instigate such measures in future! ?:D

============================
4) Relative importance of the throw
As others point out, events in the game may reduce the number of dice thrown by one side or the other. So if you get a significant number of failed activations, this will restrict the number of other dice thrown, and also make their results more significant as well - both of which will tend to skew the results.
As long as the importance of the dice roll is assigned prior to the throw, I don't really see how it affects anything. I'm not trying to model Chaos theory here (well, maybe Chaos god theory) - all I need to know is that we think that this armour save is particularly important. Yes it's subjective - but since we are testing the original theory that he tends to make the rolls he really needs to make (which is subjective to the same degree) more often than not then this is not a problem.

Combined with the "Lanchester theorem" above, this goes on to suggest that EPIC is really about reducing the number of dice thrown by your opponent (so you try to reduce his activations by loading BMs and breaking his formations etc). The side with the greates number of dice in the game is the one that will usually win.

But is that something that can be proved??
Well, this depends. One can equally argue that you are trying to maximise the number of saving throws you force him to make - the more he takes, the more likely he is to fail eventually.

So, what will your follow-up experiments be? Something to remove the rolling technique variable, such as a dice tower? Or mark the dice and use the same consistently?
Ha! Well, the course is nearly over, so any follow-up experiments are in our own time. I might ask him to use my dice for one game and run a smaller analysis to see if that corrects the problem. But actually recording all of the dice rolls is something of a pain!

Really? I would have thought the opposite would be true. I've noticed that rounded dice tend to roll a lot more, sometimes annoyingly so, than squared dice.

It is notable that Casino dice (Reputed to be the most reliable) are square-edged.
Yeah, I've heard this too, and there's an interesting thread about this on Warseer:
http://warseer.com/forums/showthread.php?t=65531

I might need to get me some square edged dice and see if it improves matters...


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 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 30, 2008 3:00 pm 
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check out this article on DakkaDakka.

it suggests that rounded dice with pits, such as GW dice, roll more 1s than square edged dice with no pits, such as Vegas Casino dice.

Who can tell how true it all is...but I would expect the Casino people would know better than most!

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 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 30, 2008 4:47 pm 
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(alansa @ Apr. 30 2008,10:00)
QUOTE
check out this article on DakkaDakka.

Thanks alansa... although I'll bet you didn't click on the link just above your post...  :;):


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 Post subject: Is my opponent just luckier than me?
PostPosted: Wed Apr 30, 2008 10:50 pm 
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yeah I did, just after i posted it!

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 Post subject: Is my opponent just luckier than me?
PostPosted: Thu May 01, 2008 9:12 am 
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Lord Inq, 1000 to 1 is improbable, but not impossible! I'm a regular one-roller, and I've used over a hundred different dice (and over 25 types, I dare say) so far, and yet I still get ones more than regularly. I've never analysed this, except for a few samples of 30 throws in which I checked the number of times I got 1-3 instead of 4-6. After doing this 3 times and getting around 20 (or more) each time I was too depressed to go on.
PS - good luck for the proposal and the PhD.  :)  :)

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