Post
Topic
Board Archival
Re: delete
by
equipoise
on 02/10/2014, 10:50:19 UTC
...

At some point I am sure the XMR team will realize they do indeed need my help and we may work something out.

But anyway the image below posted by nutildah is interesting. Check the blocks just prior to the circle.

Later guys.


~BCX~




another 4 blocks in the last minute.

By my math, with 1 block per minute mean rate, one should see 4 blocks in the same minute about once every hour or so.  Is this correct?

I see 12 blocks in 4 minutes.

We apply the Poisson distribution.

The probability that we will get 4 blocks in 4 minutes when the expected rate is 1 block per minute (4 blocks per 4 minutes) is:

p = 44 / 4!e4 ≈ 19.5%, i.e. an occurrence expected roughly every 5 minutes.

The probability that we will get 12 blocks in 4 minutes when the expected rate is 1 block per minute (4 blocks per 4 minutes) is:

p = 412 / 12!e4 ≈ 0.064%, i.e. an occurrence expected roughly every 1559 minutes which is every 26 hours.

And note that the probably we get 10 - 14 blocks in 4 minutes is going to several times higher because we sum the probabilities for each of 10, 11, 12, 13, and 14, thus an occurrence expected several times per day.

I believe the math above is incorrect, because each 1 minute trial is independent (which is one of the requirements for a Poisson distribution). Thus we have four consecutive events, two are 4 blocks in a minute and two are 2 blocks in a minute. Thus the probability is as follows.

p = (14 / 4!e1)2 × (12 / 2!e1)2  ≈ 0.000795%, i.e. an occurrence expected roughly every 125,794 minutes which is every 87 days!

If my correction is correct, we do have evidence of something rarely occurring.
The probability of observing 4 blocks in a minute when those come from Poisson distribution (the probability of a given number of events occurring in a fixed interval of time and/or space if these events occur with a known average rate and independently of the time since the last event - Wikipedia) is P(X=4) = 0.01532 (calculation here: http://www.wolframalpha.com/input/?i=Poisson+distribution+X%3D4+mean%3D1). This makes it happen about 22 times a day which is once each 65 minutes on average. When the difficulty changes those numbers could slightly vary. We don't have any statistical evidence about something fishy occurring.