Re: Bayesian boxes and expectation value

1999-05-18 Thread GSLevy

In a message dated 99-05-18 17:15:37 EDT, Jacques Mallah writes:

  You don't seem to understand:  that's NOT how to take an
 expectation value.  It bears little resemblance to the formula for an
 expectation value, regardless of what the distribution of m is. 

The concept of scales and distributions are kind of related: having a uniform 
distribution over a logarithmic scale is equivalent to having an exponential 
distribution over a linear scale.

The result if a calculation of an expectation value is predicated on the 
scale used. For example if the expectation value of the sound intensity is 
desired it could be calculated either using watts or using decibels with 
vastly different results since the sound intensity in decibels has a 
logarithmic relationship with its intensity in energy units. There are 
numerous other examples in physics in which logarithmic scales run parallel 
to linear scales. Who is to say that one particular scale is more natural 
than the other? In monetary terms are dollars more natural than francs? Is 
present day capital more natural than future compounded capital? Or is future 
capital more natural than interest? (they bear an exponential relationship). 
I still maintain that the scale issue in the Bayesian problem comes in the 
back door and must be dealt with. In the Bayesian case, the problem itself 
defines the scale to be used. And selecting a logarithmic scale (for example) 
guarantees that the expectation value of the box not chosen is exactly equal 
to m, which agrees with common sense.

  I'm not your enemy, any more than NATO is the enemy of the Serbian
people.  But I am your opponent in this debate.
Neither have you earned my friendship.

In so far as friendship is concerned, I believe that if we continue to have a 
vigorous and honest conversation, it will come naturally.

George :-)




RE: Bayesian boxes and Independence of Scales

1999-05-13 Thread Higgo James

George's point is also the main problem with Nick Bostrom's latest
paper re Adam  Eve. By inventing these exceptionally unlikely people, he
smuggles the 'paradox' in to his paper. I forget, perhaps that's what
started thread.

GS Levy wrote:

 It all depends how you measure my age. In fact, my lifeline extends 
 uninterrupted probably four billions years (or possibly more), since it
 first 
 appeared on earth, and we may even be cousins. And by the way, your
 lifeline 
 also extends that much. Joyeux Anniversaire! Happy Birthday!  :-)  
 
 George




Re: Bayesian boxes

1999-05-05 Thread Pete Harrison

I seem to have a lot of opinions about this that I never realised.  Maybe
one of you would like to explain my opinions to me.  The problem (which is
famous and not mine) is just a illustrative example, is deliberately flawed
and has a simple explanation  and reconciliation.  The interesting part of
the discussion is Stefan's equally simple strategy that achieves a better
than 1.5x expected return.

Cheers

Pete