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If you plan to RE X items, how do you calculate the odds you'll get at least 1 schem?


Felioats

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I'd like to know because it might help me decide how many items to direct my companions to make before I log off.

 

I know you don't add the chances together. Reverse engineering two items with a 20% chance to learn a schematic doesn't mean there's a 40% chance. If you flip a coin twice, there is not a 100% chance you'll get at least one Tails.

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This is a classic statistics type question. You actually need to multiply the chance that you don't get a schematic each time and subtract that from one. So 2 attempts (before the 2nd attempt) you have a 1-(0.8*0.8)=36% chance but after the 1st attempt it is still 20%
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I get it!

 

n is the number of items being reverse engineered.

d is the chance, as a decimal, that an item will teach a schematic. 10% is 0.1; 20% is 0.2.

 

1 - ((1 - d) to the power of n) = chance of learning a schematic

 

So the odds of getting an artifact schematic are:

 

1 item: 10%

2 items: 19%

3 items: 27%

4 items: 34%

5 items: 41%

6 items: 47%

7 items: 52%

8 items: 57%

9 items: 61%

10 items: 65%

Edited by Felioats
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wow nice calculation.

So is this saying that for ANY item you RE, it increase the chance of getting schematic?

 

Each time you RE an item, there's a 20%(10%) chance that you'll get the improved schematic. Cumulatively, it becomes more and more likely that you'll have the schematic, but that doesn't increase the chance that it'll pop up this particular time. Sometimes you'll make twenty-four attempts to RE a particular piece of Armouring, still not have it, but it's still only a 20% chance that the next attempt will get it. And sometimes you'll get two in a row, like I did REing a particular type of helmet yesterday.

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Given the fact that logging/reloggin has become a bit tiresome with all the alts, I like to craft between 5 and 10 items at least, depending on the chance ( 0.2 or 0.1) and depending on the prefix I'm after. For example, if I just got the Redoubt version, I'll make 10 of those to get the Veracity one. If I'm being unlucky and I got all the other prefixes first, I'll make 5.

Ideally, you'd RE 1 by 1 to save mats, but the sense of grind would be too strong and an actual waste of time. I just try to be practical and I don't calculate odds.

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Given the fact that logging/reloggin has become a bit tiresome with all the alts, I like to craft between 5 and 10 items at least, depending on the chance ( 0.2 or 0.1) and depending on the prefix I'm after. For example, if I just got the Redoubt version, I'll make 10 of those to get the Veracity one. If I'm being unlucky and I got all the other prefixes first, I'll make 5.

Ideally, you'd RE 1 by 1 to save mats, but the sense of grind would be too strong and an actual waste of time. I just try to be practical and I don't calculate odds.

 

Yeah, I decided to do this after I recently got frustrated and just directed my guys to make 15 prototype (blue) items. Then I got the artifact (purple) I wanted on like the second one.

 

That can still happen knowing this, and I'm not sure how useful it is, but it is nice to know.

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wow nice calculation.

So is this saying that for ANY item you RE, it increase the chance of getting schematic?

 

There is a difference between chance and probability. What Felioats is calculating is the probability of success given a specific number of tries.

 

IMO a better visual is the probability of continued failure versus the fixed chance of success.

 

For a 20% RE on the first attempt your chance of failure is 80%. Simple enough. Now on the second attempt while the chance of success is still only 20%, the chance of two failures in a row is 64% (80%^2). Continuing the math the probability of...

 

3 failures in a row is 51.20% (80%^3) compared to 20% chance of success

4 failures in a row is 40.96% (80%^4) compared to 20% chance of success

5 failures in a row is 32.77% (80%^5) compared to 20% chance of success

6 failures in a row is 26.21% (80%^6) compared to 20% chance of success

7 failures in a row is 20.97% (80%^7) compared to 20% chance of success

8 failures in a row is 16.78% (80%^8) compared to 20% chance of success

 

Basically, if you get a schematic before the 8th try consider yourself lucky because you beat the odds. :D

 

on a 10% RE you have to go 21 consecutive failures before the odds tip in your favor. The probability of 21 failures in a row is 10.94% (90%^21) compared to 10% chance of success.

 

Then you have the law of averages to deal with. Perform millions of REs at 20% and the ratio of successes versus failures will work out to approximately one success to four failures (1:4). Another way to look at it is one in five attempts results in a success. The problem is when someone perform 20 REs at 20% and does not see that 1:4 ratio and they come to these forums to complain about it. They complain about not getting one schematic in 20 attempts but they "conveniently forget" the fact that they got two schematic is three tries a week ago :p. But this human nature - we tend to focus on the negative :(.

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wow nice calculation.

So is this saying that for ANY item you RE, it increase the chance of getting schematic?

 

No.

 

Every individual roll is 20%. No matter how many times you did it before, it's only 20% each roll.

 

You chance, OVER TIME, is increased as odds say eventually you will hit the schematic. However each individual roll is 20% regardless of anything that has every happened before it.

 

 

This the classic gambler fallacy.

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In short, it's like a coin flip then. You got a chance of heads or tails, but each flip has its own chance of heads or tails, and doesn't really give a crap whether the last flip was heads or tails.

 

Guess I'll just keep spam making things, and RE'ing them as they come until I get an upgrade. I can always cancel what my crew are making and get all the goodies back, so it's not like I'm really wasting any materials.

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In short, it's like a coin flip then. You got a chance of heads or tails, but each flip has its own chance of heads or tails, and doesn't really give a crap whether the last flip was heads or tails.

 

Guess I'll just keep spam making things, and RE'ing them as they come until I get an upgrade. I can always cancel what my crew are making and get all the goodies back, so it's not like I'm really wasting any materials.

 

Sort of, but you honestly have to take a statistics course to get a better grasp on the situation. Even though each RE is independent from each other, the more you RE the higher the chance you will learn that recipe.

 

Take a coin flip for example, each flip of the coin doesn't effect another flip but the odds that you will have 8 heads out of 10 is very low. Here's a link which helps to explain it.

 

http://www.mathsisfun.com/data/probability-events-independent.html

 

In the case of REing, this would fall under the "Two or More Events" category. We can set up a simple calculation which will give us the odds of you NOT learning a schematic. Lets assume you have 8 mats you are going to RE and the chance you wont learn a schematic is 80% for all of them. You would set up the equation like this:

 

(0.8*0.8*0.8*0.8*0.8*0.8*0.8*0.8)

 

which gives you a result of 16.7772%. This means that theoretically you will have a 16.8% chance of NOT learning a schematic if you RE 8 items. Of course, 8 items is an extremely low sample size so you will often see irregularities.

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No.

 

Every individual roll is 20%. No matter how many times you did it before, it's only 20% each roll.

 

You chance, OVER TIME, is increased as odds say eventually you will hit the schematic. However each individual roll is 20% regardless of anything that has every happened before it.

 

 

This the classic gambler fallacy.

 

^ Forget all the fancy calculations in the thread, this guy got it right!

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Your chance, OVER TIME, is increased as odds say eventually you will hit the schematic. However each individual roll is 20% regardless of anything that has every happened before it.

 

Not really. It's unlikely you'll go on a long streak of failures, but just because you HAVE gone on a long streak of failures in no way impacts the odds of future success.

 

Here's a depressing thought for all you crafters. For those 10% success items, the odds of getting a success on your next attempt (10%) is just about the same as the odds your next attempt will be the first in a string of 22 failures. (9.8%)

 

Each and every time you RE. Depressed much?

 

edit: and P.S. My suggestion is whenever possible, never try to RE a single item at a time. Set up 5 *different* items in your crafting queue(s), so you aren't wasting mats if you happen to get the RE after the first one... and so you aren't wasting time changing characters so often by only having 1 item in the queue. Only when you're down to very few worthwhile schematics left to learn should you be either doing multiples of 1, or only having 1 item in the queue.

Edited by GnatB
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Never tell me the odds!

 

.2

.24

.288

.3456

.41472

.497664

.5971968

.71663616

.859963392

1.03195607

 

or you could just look at it simply and go 5 x .2 = 1

 

If the odds are in your favor you should at least see your schematics by your tenth attempt. Not that this will help you in the game in any way as each roll is independent of the last. Then again it really depends on how you look at it.

Edited by Corporal_Armstro
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Never tell me the odds!

 

.2

.24

.288

.3456

.41472

.497664

.5971968

.71663616

.859963392

1.03195607

 

or you could just look at it simply and go 5 x .2 = 1

 

If the odds are in your favor you should at least see your schematics by your tenth attempt. Not that this will help you in the game in any way as each roll is independent of the last. Then again it really depends on how you look at it.

 

what are your numbers?!?

 

its 20% each time.

 

.20

.20

.20

.20

.20

.20

.20

.20

.20

 

this never changes

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Not really. It's unlikely you'll go on a long streak of failures, but just because you HAVE gone on a long streak of failures in no way impacts the odds of future success.

 

Here's a depressing thought for all you crafters. For those 10% success items, the odds of getting a success on your next attempt (10%) is just about the same as the odds your next attempt will be the first in a string of 22 failures. (9.8%)

 

Each and every time you RE. Depressed much?

 

edit: and P.S. My suggestion is whenever possible, never try to RE a single item at a time. Set up 5 *different* items in your crafting queue(s), so you aren't wasting mats if you happen to get the RE after the first one... and so you aren't wasting time changing characters so often by only having 1 item in the queue. Only when you're down to very few worthwhile schematics left to learn should you be either doing multiples of 1, or only having 1 item in the queue.

 

Even MORE depressing is if you are chasing specific schematics. So, for tier 1(overkill,critical,redoubt) you have a 1 in 5 chance of simply learning a schematic and then a 1 in 3 chance of learning the one you want. So, if you are chasing an overkill chest piece you have a 1/15 chance of getting it per attempt, or a 93.3% chance of failure. So to get a specific item, it would take 24 times to tip the odds in your favor...of course that assuming you can relearn the same schematic which they fortunately fixed a while back. Being nearly 7 years removed from my now unused math major I can't remember how to work the probability without replacement on the second event.

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what are your numbers?!?

 

its 20% each time.

 

.20

.20

.20

.20

.20

.20

.20

.20

.20

 

this never changes

 

His math is suspect, but he has the right idea. While the percentage chance of success never changes the probability of continued failure does go down. On the first attempt the odds of success versus failure are 20%/80%, however the odds of success versus seven failures in a row is all but a coin flip - 20% chance of success versus 20.97% chance of seven failures. And the odds of success are actually better than that of eight failures 20%/16.78%

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His math is suspect, but he has the right idea. While the percentage chance of success never changes the probability of continued failure does go down. On the first attempt the odds of success versus failure are 20%/80%, however the odds of success versus seven failures in a row is all but a coin flip - 20% chance of success versus 20.97% chance of seven failures. And the odds of success are actually better than that of eight failures 20%/16.78%

 

There no such thing as "the probability of continued failure". There's only (a) the probability of a single attempt, and (b) the probability of learning m schems in n attempts. Assuming we consider m >= 1, then the probability mentioned in (b) is higher for high n than low n. But it doesn't matter at all whether you have previously failed; no probabilities change when you continue to fail (or succeed).

Edited by Telanis
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Yep. The odds of getting a success on THIS attempt may be about the same as the odds that the next 7 attempts will be failures.

 

But once you've failed 6 times, it isn't 50/50 odds on the next attempt. The next attempt is still only 20% chance of success... and ~20% chance that the next 7 attempts will be failures.

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There maybe no "the probability of continued failure" but there is "the probability of continuious failure". We are talking about future events.

 

"The odds that one will get at least 1 schem" will always be less than 100% regardless of the number of RE.

 

When the number of RE approaches infinity, "the odds that one will get at least 1 schem" becomes closer to 100%

 

http://i48.tinypic.com/v2r9yw.jpg

 

The following table may mean nothing or it may help some to visualize.

 

Roll1	Roll2	Roll3	Roll4	Roll5		Pr
0.8	0.8	0.8	0.8	0.8		0.32768
0.8	0.8	0.8	0.8	0.2		0.08192
0.8	0.8	0.8	0.2	0.8		0.08192
0.8	0.8	0.8	0.2	0.2		0.02048
0.8	0.8	0.2	0.8	0.8		0.08192
0.8	0.8	0.2	0.8	0.2		0.02048
0.8	0.8	0.2	0.2	0.8		0.02048
0.8	0.8	0.2	0.2	0.2		0.00512
0.8	0.2	0.8	0.8	0.8		0.08192
0.8	0.2	0.8	0.8	0.2		0.02048
0.8	0.2	0.8	0.2	0.8		0.02048
0.8	0.2	0.8	0.2	0.2		0.00512
0.8	0.2	0.2	0.8	0.8		0.02048
0.8	0.2	0.2	0.8	0.2		0.00512
0.8	0.2	0.2	0.2	0.8		0.00512
0.8	0.2	0.2	0.2	0.2		0.00128
0.2	0.8	0.8	0.8	0.8		0.08192
0.2	0.8	0.8	0.8	0.2		0.02048
0.2	0.8	0.8	0.2	0.8		0.02048
0.2	0.8	0.8	0.2	0.2		0.00512
0.2	0.8	0.2	0.8	0.8		0.02048
0.2	0.8	0.2	0.8	0.2		0.00512
0.2	0.8	0.2	0.2	0.8		0.00512
0.2	0.8	0.2	0.2	0.2		0.00128
0.2	0.2	0.8	0.8	0.8		0.02048
0.2	0.2	0.8	0.8	0.2		0.00512
0.2	0.2	0.8	0.2	0.8		0.00512
0.2	0.2	0.8	0.2	0.2		0.00128
0.2	0.2	0.2	0.8	0.8		0.00512
0.2	0.2	0.2	0.8	0.2		0.00128
0.2	0.2	0.2	0.2	0.8		0.00128
0.2	0.2	0.2	0.2	0.2		0.00032

					1

 

Note statisics is all theoretical. It is possible to fail million times in a row even the probability of a single success is 99.9999999%. Statisics become accurate when the number of events approaches infinity

Edited by Banegio
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I don't calculate, I just R/E :) The more you calculate, the more you hesitate. Keep that in mind.

 

You ain't kidding.I have created more swear words REing then when I was in the military.I could get pretty creative then.:eek:

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