DefaultTrust changes

[The Sceptical Chymist]

Whoa, you were fast on detecting that. Is there any official reason why? I do agree with your previous statement in that making the process more democratic a step forward.

Lauda's inclusion and exclusion from DT1 has been a see-saw for quite some time now, so I'm not shocked that he/she's not on it anymore--but that could change. 

I still have not figured out why TECSHARE has me included.  I would not have expected that.  Ever.

There are also many examples of people leaving many controversial ratings over time who are already on DT who see no real pushback against their ratings. There are also examples of people facing retribution in the form of frivolous negative ratings (bill gator), and trust exclusions (bill gator and teeGUMES) for making statements that goes against the "crowd".

I agree with this, and I'd excluded teeGUMES for about 30 minutes before I realized I was making an emotional decision, after which I un-excluded him.  And as far as bill gator goes, I stood up for him and will still do so.  He's a good guy and really didn't deserve the shitty treatment he got.

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[Quickseller]

No. if Lauda is excluded from DT1, he cannot be on DT2. I think your assumptions as to whose votes count might be flawed.

If you are on DT1, your trust list flows down regardless if your ratings show up or not.

Loyce is right. Excluded DT1 members can't "vote" for (or against) DT2 members. So Lauda gains DT2 "strength" compared to the previous DT1 "strength" because exclusions from TECSHARE et al don't count against Lauda anymore.

https://bitcointalk.org/index.php?action=trust;full;dt

A review of the OP and the rules for DT, it appears you are right.

This appears to be a flaw in the logic of how DT1/2 voting works. 

[nutildah]

I always thought that was a bit of an odd feature of the whole DT system. Being on DT2 has more power than being on DT1 but being voted off. Excluded DT1 votes don't even count for flags.

[LoyceV]

I still have not figured out why TECSHARE has me included.  I would not have expected that.  Ever.

See https://bitcointalk.org/index.php?topic=5047060.msg51714652#msg51714652.

[Veleor]

This month 106 users were eligible. <...>

Removed [13]:

phantastisch
Anduck
arulbero
Lydian
BitcoinPenny
ezeminer
MaoChao
Last of the V8s
LeGaulois
PHI1618
kenzawak
chimk
ICOEthics

Added [15]:

Dabs (Trust list)
monkeynuts (Trust list)
ibminer (Trust list)
vizique (Trust list)
hedgy73 (Trust list)
EcuaMobi (Trust list)
zazarb (Trust list)
LFC_Bitcoin (Trust list)
actmyname (Trust list)
WhiteManWhite (Trust list)
Ale88 (Trust list)
bobita (Trust list)
Matthias9515 (Trust list)
Silent26 (Trust list)
lovesmayfamilis (Trust list)

[fillippone]

Interesting thing: being not included in DT1 in one month because random rotation doesn’t mean next month you will be included back.
Very unlucky user Babo was put out of DT1 last month and still outside DT1 also this  month even if he still qualify.
I don’t know if it already happened to someone else.

[babo]

Ahaha i'm unlucky one
I know my history of luck, or better.. no luck

[LFC_Bitcoin]

Ahaha i'm unlucky one
I know my history of luck, or better.. no luck

You’ll be back my friend, don’t worry. It won’t happen again, surely.

[suchmoon]

Interesting thing: being not included in DT1 in one month because random rotation doesn’t mean next month you will be included back.

~0.2% chance of that happening two months in a row. Eventually once we get to 250 candidates (or whatever theymos' expectation was) it will be much more frequent.

[bones261]

No. if Lauda is excluded from DT1, he cannot be on DT2.

Lauda is blacklisted from DT1 (not excluded), and is still on DT2 (proof).

He wiped his trust&distrust lists a couple weeks ago and  washed himself out.

Wiping your trust list only disqualifies you from DT1 when Theymos does his monthly update. It does not instantly disqualify you. However, when Lauda was removed from DT1, it was not the result of Theymos doing an update. Lauda's removal also was not the result of more people on DT1 distrusting her than trusting her.

[theymos]

~0.2% chance of that happening two months in a row. Eventually once we get to 250 candidates (or whatever theymos' expectation was) it will be much more frequent.

If you're looking at a particular person, their chance of being excluded in both a month with 104 eligible and the next month with 106 eligible is ~0.2%. But the chance that any one or more people already excluded in the first month are also excluded in the second month is, I believe, 1 - [(102 choose 100) / (106 choose 100)] = 99.9997%

[fillippone]

~0.2% chance of that happening two months in a row. Eventually once we get to 250 candidates (or whatever theymos' expectation was) it will be much more frequent.

If you're looking at a particular person, their chance of being excluded in both a month with 104 eligible and the next month with 106 eligible is ~0.2%. But the chance that any one or more people already excluded in the first month are also excluded in the second month is, I believe, 1 - [(102 choose 100) / (106 choose 100)] = 99.9997%

I might be hugely wrong here:
Probability of a single user being excluded from the two DT1 round as defined (100 out of 104 and 100 out of 106) is correct as l’you already found:
4/104*6/106~0,2%.
Probability of any user excluded from first selection to be excluded also from second one:
1-(100/106)^4~20.79%
Please check me

EDIT: typo on the first result
EDIT: already spotted by Quickseller
EDIT: after a little mumbling on Quickseller observations, I stand with my answer. Tomorrow I will double check.

[Quickseller]

~0.2% chance of that happening two months in a row. Eventually once we get to 250 candidates (or whatever theymos' expectation was) it will be much more frequent.

If you're looking at a particular person, their chance of being excluded in both a month with 104 eligible and the next month with 106 eligible is ~0.2%. But the chance that any one or more people already excluded in the first month are also excluded in the second month is, I believe, 1 - [(102 choose 100) / (106 choose 100)] = 99.9997%

The chances of any one or more people already excluded in the first month also being excluded in the second month (when there are 104 eligible in the 1st month and 106 eligible in the next month) is:
4 * [1-(100/106)], or ~22.4%

In other words, it is the chances of a single individual person being excluded in the second month, times the number of people excluded in the 1st month.

edit:

I might be hugely wrong here:
Probability of a single user being excluded from the two DT1 round as defined is 4/104*6/106~0,02%

Your formula:
4/104*6/106
is correct, however you converted into a percentage incorrectly, the chances of a person being excluded two months in a row, one with 104 eligible people and the other with 106 eligible is 0.217%

Probability of any user excluded from first selection to be excluded also from second one:1-(100/106)^4~20.79%

Your exponent should be a multiplication, and there should be an additional bracket because of the order of operations.

[theymos]

The chances of any one or more people already excluded in the first month also being excluded in the second month (when there are 104 eligible in the 1st month and 106 eligible in the next month) is:
4 * [1-(100/106)], or ~22.4%

Damn it, I simulated it, and you seem right. I suppose that my model of the situation was wrong because it actually does matter that the first month has already happened, whereas I was trying to eliminate the specificity of this.

[fillippone]

The chances of any one or more people already excluded in the first month also being excluded in the second month (when there are 104 eligible in the 1st month and 106 eligible in the next month) is:
4 * [1-(100/106)], or ~22.4%

Damn it, I simulated it, and you seem right. I suppose that my model of the situation was wrong because it actually does matter that the first month has already happened, whereas I was trying to eliminate the specificity of this.

Guys I am again on this.
I thought about this problem quite extensively during this weekend on the italian riviera.

I think Quickseller formula is not correct as it does allow repetition, while we must find a solution without repetition (if a user is selected, it cannot be taken out again on the same round).
I think Theymos was then on the right path using binomial coefficients, so I am going to use the same technique.

The right probability of any of the 4 excluded in the first round to be excluded in the second round is equal to 1 - the probability of everyone of such 4 to be selected:

1-C(100,4)/C(106,4)=0.210654248

another less intuitive method give the  same exact result:

1-C(102,6)/C(106,6)=0.210654248

(probability of being amongst the 6 excluded from the second extraction chosen by the 100 selected from the first extraction + the 2 new addition).

I am almost sure about this, but please double check me again.
Theymos said he simulated and got a result very similar to Quickseller, this scares me, also because I saw LoyceV and other heavyweight meriting previous solution... shall I go back to school?

EDIT: Forgot to mention, but clearly an hypothesis here: every candidate on the first round is a candidate also for the second round. This simplifies calculations, when we agree on the solution, we'll be able to remove this hypothesis.

[Quickseller]

The query is:
What are the chances that at least one person who was not included in DT1 in July are also not included in DT1 in August. There were 4 people not included in July, there were 106 candidates for DT1 in August with only 100 spots. It is assumed that all 4 people will continue to be eligible in August.

The query can be rewritten/simplified as:
What are the chances of at least 1 of 4 specific people not being included in DT1 in a month in which there are 106 candidates and 100 spots?

You can start by calculating the chances of any one person not being included on DT1 with 100 spots, and 106 candidates with the following formula:6/106
The 6 represents the number who will not get a DT1 spot, and the 106 represents the total number of candidates. The formula is calculated to 5.66%. In other words, there is a 5.66% chance that any one person will not be included in DT1 given 106 candidates and 100 spots.

Since there are 4 opportunities for the above outcome to happen, we would multiple the above result by 4.

Every candidate has the same chances of being not included, and there may be some months in which more than one in the list of 4 is also not included in the following month

I saw LoyceV and other heavyweight meriting previous solution

Unless there is a solution in another thread, LoyceV did not merit any previous solution other than mine (he did merit mine). bones261 is the only one who merited the previous solution, but he also gave more merit to my solution.

[fillippone]

The query is:
What are the chances that at least one person who was not included in DT1 in July are also not included in DT1 in August. There were 4 people not included in July, there were 106 candidates for DT1 in August with only 100 spots. It is assumed that all 4 people will continue to be eligible in August.

The query can be rewritten/simplified as:
What are the chances of at least 1 of 4 specific people not being included in DT1 in a month in which there are 106 candidates and 100 spots?

Correct

You can start by calculating the chances of any one person not being included on DT1 with 100 spots, and 106 candidates with the following formula:6/106

The 6 represents the number who will not get a DT1 spot, and the 106 represents the total number of candidates. The formula is calculated to 5.66%. In other words, there is a 5.66% chance that any one person will not be included in DT1 given 106 candidates and 100 spots.

correct

Since there are 4 opportunities for the above outcome to happen, we would multiple the above result by 4.

Not correct, sorry.
Source: Combinatorics/Probability Calculation.
I also discussed this solution with some error-proof individual. He agreed on my solution (this is not appeal to authority, this is only to double check my calculations).

Every candidate has the same chances of being not included, and there may be some months in which more than one in the list of 4 is also not included in the following month

I saw LoyceV and other heavyweight meriting previous solution

Unless there is a solution in another thread, LoyceV did not merit any previous solution other than mine (he did merit mine). bones261 is the only one who merited the previous solution, but he also gave more merit to my solution.

When I said previous solution I was referring to your solution, of course, the last solution above my post.

 

[suchmoon]

If you're looking at a particular person

Yes, the chance of babo being excluded twice in a row.

any one or more people already excluded in the first month are also excluded in the second month

Intuitively that chance would be ~100 times greater, i.e. around 20%. Sounds close enough to the debate going on above but they seem to assume that all 104 candidates from the first month are also eligible in the second month, which may or may not be the case.

[fillippone]

If you're looking at a particular person

Yes, the chance of bobo babo being excluded twice in a row.

any one or more people already excluded in the first month are also excluded in the second month

Intuitively that chance would be ~100 times greater, i.e. around 20%. Seems close enough to the debate going on above but they seem to assume that all 104 candidates from the first month are also eligible in the second month, which may or may not be the case.

FTFY!
poor Babo!

[suchmoon]

FTFY!
poor Babo!

Apologies to babo. My excuse is that I was binging Wynonna Earp yesterday.