100 pages or so 'disappeared' from another forum and many from yet another.
I believe @Optimissed has been muted by chess.com.
His account shows as online right now.
But his posts seem to have disappeared from at least three forums.
The sad thing is that @Optimissed has just got something half right and I had credited him for it.
@8652
"Bayesian analysis can't solve chess, but it is the right way to deal with such questions."
++ If you want to discuss that, then let us take an easier example to reason on.
Say I toss a loaded coin 106 times and it lands heads 106 times.
If we now toss the loaded coin 30 more times, what is the probability it lands tails at least once?
It's a good question as an illustrative example. As always, prior beliefs matter (the general pattern is that the amount they matter should go to zero as the amount of data goes to infinity).
Pretend we haven't seen any data yet. A prior belief consists of a probability distribution on the unit interval, indicating how likely we think is is (before we have seen any data) that the coin is loaded in a way that would make it come up heads a particular fraction of the time.
For example one prior belief might be very specific - that there is a 98% chance that the coin is fair, a 1% chance that the coin has two heads and a 1% chance that the coin has 2 tails. This is an extreme state of belief because it is inconsistent with the possibility that the coin has a heavy side, so that it comes up heads 55% of the time, or whatever. It's generally best not to exclude any possibility that is not absolutely certainly not true.
At the other extreme, a very neutral prior belief (in one sense) would be a uniform distribution. The possibility that the coin is weighted so that heads comes up a proportion p of the time is independent of p. i.e. 90% heads is exactly as likely as 30% is exactly as likely as 50% heads and so on (it can be easier to think of this in intervals - eg. it is equally likely that p is between N/100 and (N+1)/100 for any N from 0 to 99.
It's better to pick something like that (there are sophisticated reasons to pick something slightly less uniform, but it's not a big deal).
Anyhow, then we do the Bayesian inference. We first work out the probability of the evidence given the prior probability for ever probability p. Then we apply Bayes rule.
The evidence was that we got 106 heads. Here is the probability distribution for p given that evidence compared to the distribution before the evidence (the red line which is flat - a uniform probability). What you see is that 106 elements of evidence is enough to be pretty sure the probability of a head is quite close to 1 (unlikely to be as low as 0.9, say).
We can actually estimate the probabilty of a head by completing the inference by averaging over all possible values of p. I have put the answer in the title of the graph:
So the answer to your question is that with these neutral assumptions, we would think there was just under 1% chance of the next result being a tail. This makes intuitive sense. If you do this in an analytical way, you can think like the following - it's rather neat:
First we have no data. So let's make a prior by pretending we have a tiny amount of data. Say half a sample which was a head and half a sample which was a tail.
Then when we have our real data, we add the data to our prior data and we have 106.5 heads and 0.5 tails, which we view as indicating the true probabilities - i,e, just over 99.5% chance of heads.
(What I did was more like starting with a prior of 1 head and 1 tail. For technical reasons 0.5 and 0.5 is considered a slightly better choice).
With this viewpoint, you can see that the more data you have, if it's all heads, the nearer the probability gets to 1. But it never gets there. This is appropriate as it is obvious that no amount of data excludes the possibility that there is a low but finite probability of tails. It just gets better at excluding larger probabilities of tails from being likely.