[metrics-bugs] #28555 [Metrics/Analysis]: Assess methodology for modern privcount Tor user counts

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#28555: Assess methodology for modern privcount Tor user counts
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 Reporter:  arma              |          Owner:  metrics-team
     Type:  task              |         Status:  new
 Priority:  Medium            |      Milestone:
Component:  Metrics/Analysis  |        Version:
 Severity:  Normal            |     Resolution:
 Keywords:                    |  Actual Points:
Parent ID:                    |         Points:
 Reviewer:                    |        Sponsor:  Sponsor19
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Comment (by teor):

 I just wrote about this in #tor-project:

 The 8 million user figure was measured using PSC, which does unique counts
 across multiple relays. We won't be implementing unique counts in
 PrivCount in Tor, because it's an entirely different protocol, which takes
 ~24 hours to aggregate the counts.

 Pages 8-11 of https://export.arxiv.org/pdf/1809.08481 give a few more
 details about the methods we used to calculate the 8 million figure.

 The best way to get a better estimate out of metrics, is to measure how
 many consensuses a client downloads in 24 hours, and update metrics'
 estimate. (We can't really do anything to measure clients that move IP
 addresses, or clients that are only online for part of a day.)

 Maybe we could measure the average number of consensuses per day per IP
 address using PrivCount? But then we'd be keeping sensitive info in RAM
 (IP addresses).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28555#comment:3>
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