[tor-bugs] #18167 [Metrics]: Don't trust "bridge-ips" blindly for user number estimates

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#18167: Don't trust "bridge-ips" blindly for user number estimates
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 Reporter:  karsten  |          Owner:
     Type:  defect   |         Status:  new
 Priority:  Medium   |      Milestone:
Component:  Metrics  |        Version:
 Severity:  Major    |     Resolution:
 Keywords:           |  Actual Points:
Parent ID:           |         Points:
  Sponsor:           |
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Comment (by dcf):

 > To summarize my plan, here's what I'd like to do:
 > 1. If a bridge reports both a `"dirreq-v3-resp"` and a `"bridge-ips"`
 line, check if the first number is smaller than 10 times the second
 number; if not, ignore these directory-request statistics reported by this
 bridge.
 > 2. If a bridge only reports a `"bridge-ips"` line and no
 `"dirreq-v3-reqs"` line, assume that the country distributions are the
 same, which is what we're doing right now.
 > 3. If a bridge reports a `"dirreq-v3-reqs"` line, use that for user
 number estimates and ignore the `"bridge-ips"` line in case it's present.

 Thanks for looking into this. That explains my confusion. I assumed that
 it was already using `"dirreq-v3-reqs"`, not `"bridge-ips"`. I.e. I
 thought (3) was already in effect.

 I don't think we should do (1). The old `"dirreq-v3-resp"` and
 `"dirreq-v3-reqs"` numbers are correct, it's just that they are being
 wrongly apportioned to countries. But they still count the total
 accurately, I believe. We knew what the consequences would be back then,
 that meek users would be wrongly counted as being mostly from the U.S. We
 expected, after merging #13171, that the count of U.S. users would go down
 and other countries would go up. Ignoring those counts would be ignoring
 around 20% of bridge users through 2015.

 Agreed on (2) and (3).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18167#comment:2>
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