[tor-bugs] #6232 [Analysis]: Make entropy-over-time graph

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#6232: Make entropy-over-time graph
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 Reporter:  arma         |          Owner:              
     Type:  enhancement  |         Status:  needs_review
 Priority:  normal       |      Milestone:              
Component:  Analysis     |        Version:              
 Keywords:               |         Parent:              
   Points:               |   Actualpoints:              
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Comment(by asn):

 Replying to [comment:30 robgjansen]:
 > Replying to [comment:29 asn]:
 > > Replying to [comment:28 robgjansen]:
 > > > We are still missing the graph where each of the plots are
 represented as a percentage, computed as: (entropy / max_entropy). See my
 first post above.
 > >
 > > Say, if the entropy of the current consensus is 8 bits, and the
 maximum possible entropy is 11 bits, do you think that 70% would be the
 correct figure in this case? It seems like that the logarithmic scale
 gives us an overrated percentage.
 > >
 > > Maybe we should transform the values to the linear scale (`2^8/2^11`)
 to get a more intuitive percentage. Or is there a better way to represent
 this comparison?
 >
 > I don't understand your opposition, but it shows that the meaning of
 entropy to describe anonymity is not well understood. (I've been asking
 'WTF does entropy mean?' all along.)
 >
 > Read [http://www.freehaven.net/anonbib/cache/Diaz02.ps.gz this paper],
 particularly Section 3.

 Oh, I did not oppose your idea; I also agree that entropy and bits are not
 intuitive ways of measuring diversity or whatever we are trying to measure
 here.

 What I tried to say is that '''maybe''' ''degree of anonymity'' is not the
 most intuitive way of graphing ''How far away are we from the ideal
 network (wrt bandwidth weights) of 'n' nodes''. I'm saying this because
 entropy is measured in logarithmic units and the logarithmic scale is
 harder to understand than the linear scale (IMO).

 For example, what does a `0.76` ''degree of anonymity'' means? It does
 '''not''' mean that the ''current Tor network'' is 76% of a ''perfect Tor
 network'' because of the logarithmic nature of entropy. That's the reason
 I asked if it would be more helpful to conver the <entropy>/<max entropy>
 figure to the linear scale.

 In any case, ''degree of anonymity'' should be more intuitive than plain
 entropy: I coded the change in branch `bug6232` of `git://gitorious.org
 /metrics-tasks/metrics-tasks.git` (https://gitorious.org/metrics-tasks
 /metrics-tasks/commit/e54b4278361184bf6ff90f189898668160474f2f).

 Also, thanks for the link to the paper.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6232#comment:31>
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