What fraction of exit relays exit from a different IP than is in their descriptor?
If we tell people to use e.g. VisiTor to see how many of their web hits are from Tor, the visitor scripts only look at descriptors and the consensus documents.
Karsten has been working on integrating the tordnsel output with the Exonerator output. How much error is there if you only look at the addresses in the normal directory documents? That is, how much should we care about making sure to keep the tordnsel (or soon, torbel) output integrated?
By fraction I probably mean 'fraction by exit capacity'.