[Mini-Guide] Mabinogi Repair % System Is a Lie?

• Rime wrote on 2010-05-12 03:44

  Quote from Kazuni;34044:

  So what you're saying is that repair has a fixed outcome and % doesn't matter because it's fixed?
  
  And as a response to.. your response.. about the marble thing, it was just an example for the chance of going back in time, and the angle of the hand and possible influences are not considered factors, as repairing in mabinogi is purely electronic and not dependent on outside factors at all.

  
  
  "Electronic" probabilities are dependent on complex algorithms. In Mento's example, the difference between OG1 and OG2's RNG algorithms is that OG1's must not have varied with passing time. That said, since we cannot determine the working of Mabi's algorithms and whether or not the algorithms significantly affect the repair rate, this whole unblessed perfect repair vs. point by point repair is pretty inconclusive.
• Mentosftw wrote on 2010-05-12 04:19

  Quote from Kazuni;34044:

  So what you're saying is that repair has a fixed outcome and % doesn't matter because it's fixed?
  
  And as a response to.. your response.. about the marble thing, it was just an example for the chance of going back in time, and the angle of the hand and possible influences are not considered factors, as repairing in mabinogi is purely electronic and not dependent on outside factors at all.

  
  
  In a sense, it IS fixed. Every experiement is always fixed. You just don't know the outcome yet till you try it :P
  Let's say a tossed die ends up a 4, that's one experiment. It'll always be a 4 no matter how many times you can reverse time and watch it roll, it'll always be a 4. The randomness of chance only exists the moment an experiment with odds is about to happen. Basically, when you don't know the outcome and only the odds. The odds only show you the ratios of the outcomes. Once it happens, you can say that outcome for that experiment was a one hundred percent "chance" it would happen.
  What I'm trying to get at both logically and mathematically is that if you could choose both point by point and perfect at the same time, you would get a different result logically because they are two different options but also mathematically because point by point and perfect presents the same (you can argue differently because of the RNG of mabi) odds but chance will "choose" a different outcome (unless they both end up with the same outcome by chance of course, and that chance of both of them either having the same or a different outcome is another discussion and one dealing with hypothetical situations that can't happen (going back in time, as of now anyway)).
  
  I digress, the main point is that because of the unknown algorithim of this game's system and because of how it deals with "chance", it changes things. At the same time it brings a bit of irony as all this is almost as if the blacksmiths of mabi "choose" whether or not to fail with your equipables.
• Trigger wrote on 2010-05-12 06:44
  This entire guide assumes from the get-go that Mabinogi actually uses a correct probability model, which is a pretty big assumption given that we have no source code to prove it.
  
  Assuming for the sake of argument that Mabinogi actually does use correct probability, six years of mathematics studies doesn't mean your word is law. Tossing out some credentials lends more weight to your words, but it doesn't mean you're infallible. "Nothing by mere authority" ---Royal Society motto
  
  
  Point-by-point and full repair are identical from a probability standpoint.
  
  
  

  
  
  • My chance of flipping heads on a coin is 50%.
    
    
  • If I flip twice, my chance of getting heads both times is 50% * 50% = 25%.
    
    
  • The chance for each individual flip is 50%. That never changes.
    

  
  
  
  Assuming no Holy Water is involved:
  
  
  

  
  
  • My chance of repairing a point of durability at Ferghus is 90%.
    
    
  • If I repair twice, my chance of repairing successfully both times is 90% * 90% = 81%.
    
    
  • The chance for each individual repair is 90%. That never changes.
    

  
  
  
  All the arguing that has taken place in this thread is nothing but semantics. The probability of repairing a single point is always the same! That probability stacks on top of itself the more consecutive points you repair. You can't thwart the numbers by considering each consecutive repair a new set of calculations; it's the same either way you look at it.
  
  The advantage to repairing point-by-point is what has already been stated -- repairing one point at a time allows you to rebless your gear should a repair fail.
• alphabetical wrote on 2010-05-12 07:21
  Point by point and perfect repairs DO have different approaches but the BEGINNING and END RESULTS are the same and that's what matters. Who wants to know what happens between those two points in time? All we want to know is how long the weapon will last.
  
  Lets say you have a 0/3 dura weapon. If you choose to repair point by point, obviously you're not going to repair it once, and leave with 1/3 dura right? (or maybe 0/2) No, you're going to repair it until it is either 3/3, 2/2, 1/1 or broken.
  
  Repairing point by point, 3 times in a row:
  -Chance 3/3 dura left = 85.7375%
  -Chance 2/2 dura left = 13.5375%
  -Chance 1/1 dura left = 0.7125%
  -Chance 0/0 dura left = 0.1250%
  
  Perfect repair has the exact same chances for the 4 different outcomes above. You can't compare the 95% success rate of a single point repair to a ~85% success rate of a perfect repair of 3 points.
• Rime wrote on 2010-05-13 05:57
  Actually, blessed point by point vs blessed perfect repair is inconclusive as well. We still don't know whether or not the increase in repair rate is applied to all points in "perfect repair" or if the bonus is taken off for the rest of the repair once a failure occurs. Since the blacksmith doesn't stop the repair and return your weapon in the instance of a failure, I'm inclined to think that there must be some kind of benefit to perfect repairs other than saving a few seconds.
• Trigger wrote on 2010-05-13 06:13

  Quote from Rime;34925:

  Actually, blessed point by point vs blessed perfect repair is inconclusive as well. We still don't know whether or not the increase in repair rate is applied to all points in "perfect repair" or if the bonus is taken off for the rest of the repair once a failure occurs. Since the blacksmith doesn't stop the repair and return your weapon in the instance of a failure, I'm inclined to think that there must be some kind of benefit to perfect repairs other than saving a few seconds.

  
  
  JP wiki says blessing applies only to the first point in a perfect repair, or until a point is failed (not sure of the wording since I'm taking this from Google Translate, which is inaccurate at best). Given the reputation of the JP wiki I'd be inclined to believe it.
• foogro wrote on 2010-05-13 18:43
  Couple comments here (maybe I missed some of the discussion above):
  
  1) Independence:
  We still don't know whether mabinogi repair rates are independent. For example, is your first repair at 98% really 98%? If you have a success, does it affect your second repair rate? Perhaps on average, you get 98%, but making a mistake on one point is likely to cause you to make a mistake on a second point. For example, for Edern to fail consecutively on 2 repairs (on an unblessed item), if each repair is independent, two consecutive failures would occur with expectation once every 2500 points of repair. I'm not sure if that's the case, but I've had him fail 3-4 points on me in a single repair of maybe 10 points. It is possible that there is some correlation.
  
  Take an extreme example: suppose that your weapon is brand new. Edern will repair at 99% if he hasn't failed yet, so he fails on average once every 100 points. However, once he fails, his repair rate for the next 2 repairs drops to 50%. Then he is back at 99% again regardless of whether those points were successful or unsuccessful. On average, this repair rate is (slightly above) 98%, about 98.04%. However, you are very likely to fail more than 1 points at a time.
  
  (This is, btw, one of the intricacies in Warcraft 3 critical rate computation. The first attack actually has very low critical rate, but after each failure to critical, the next hit has a higher probability to critical. Some people actually attack creeps a few times until they get several hits without critical, and go into battle to hit high probability criticals.)
  
  2) Variance
  
  Yay, more statistics! Anyway, another reason you get pissed at repairs is accumulated variance, not just expectation (which has been the sole focus up to this point). Variance expresses the randomness of the repair process. If you repair 1 point at 98%, you have a variance of (1-0.98)^2*0.98+(0.98^2)*0.02, which is approximately 0.02. Standard deviation, which is the square root of variance, is 0.14 points. What does standard deviation tell you? This is not a precise definition, but std dev gives you an idea of the likely range of failures. So basically, the number of points you fail on average per point of repair is 0.02, but you're likely to fail between 0.02 plus/minus 0.14 points.
  
  Given N points of repairs (assuming independence), std dev grows with sqrt(N), so 100 point repairs gives you a std dev of 0.14 points times 10, which is 1.4. Your expectation is 2 failures, but there's a high probability of failing between 0.6 and 3.4 times. Don't be surprised if Edern fails 3-4 points on your sword. If he fails 6 times though, then consider yourself one of the 3% of people who have met great misfortune.
  
  3) If you want to try to build a model of repair correlations (holy water, consecutive fails, etc) it will be extremely difficult because of the variance. You will need to sample maybe 10000 points of repairs to get a fairly accurate model. T_T
• Trigger wrote on 2010-05-14 05:26

  Quote from foogro;35111:

  You will need to sample maybe 10000 points of repairs to get a fairly accurate model. T_T

  
  
  Hence why we simply say it's straight probability and accept whatever misfortune we happen to have while repairing. That, or make long threads trying to explain something we should all have accepted by this time (I mean, come on, it's been two years people <_<).
• Stevenjr626 wrote on 2014-06-12 18:31
  I totally agree with you. The probability of point-by-point is the best. Speaking from experience. You do lose a significant amount of % when repairing by "Whole repair".
  Thank you for your post!
• M wrote on 2014-06-16 18:50

  Do not post in topics (effectively bumping it up to the top of the list) where the last reply is more than 30 days old. This is known as "necro posting". You are more than welcome to create a new topic if your search results only turn up old threads. Some exceptions apply, such as guides and the foreign mabinogi section. If you feel like bumping an old thread instead of making one would be beneficial then ask a staff member through PMs.

  
  
  To those who see this as a horrible necro, it is not. This is a guide and thus exempt, no mo reports pls
• Zekkii wrote on 2014-06-24 10:09
  You can't represent full repair as a single equation or number, as that does not represent the chance or outcome of more than one point failing to repair. The golf ball scenario is either misleading or wrong, because the odds would change as the person draws golfballs eventually leading them to pick red balls or run out of red balls to pick; basically this is gamblers fallacy or the opposing fallacy. A person can go their entire mabi lifetime without failing a repair point, it is just astronomically unlikely unless they don't repair very much in that lifetime. There's no reason to assume that there is any difference between full repairs and point by point repairs in terms of failing or succeeding, with the exception of re-blessing (EDIT: this is assuming you repair the same amount of points, of course).
  
  A simpler and more accurate way to present this to someone, is to tell them that you have a 2% chance to fail provided 98% unblessed. With a 2% chance to fail upon each repair, it would take 50 repairs on average to fail 1 point (0.02 * 50 = 1) so it should be assumed that if you fail more often then that then you are unlucky, but less often then you are lucky. However getting severely lucky or unlucky isn't grounds to assume the system is a lie either, so don't.
• Kouki wrote on 2014-06-26 08:28
  Has anyone ever had the Bard Camp's Art, Tara blacksmith, or Cobh blacksmith fail? Of all of the times I have repaired with thees NPCs(usually full repair), I have never gotten failures...
• Helson wrote on 2014-07-27 07:58
  I might try those, we'll see what happens. XD
• Cookiebunny wrote on 2014-07-31 02:47
  Okay, so basically this thread (both the OP and the arguments) propose point-by-point repair is better. Right?
• ironwoman wrote on 2014-07-31 02:53

  Quote from Cookiebunny;1236080:

  Okay, so basically this thread (both the OP and the arguments) propose point-by-point repair is better. Right?

  
  
  Correct.
  
  Also, you don't have to repair your equips to full durability.
  My hat is almost always at like 8/13, and I only repair a point or two when I'm not feeling lazy.
  
  My weapons are a different story though.