I think you are confusing the median with the mean: https://en.wikipedia.org/wiki/Median https://en.wikipedia.org/wiki/Mean
Taking the median instead of the mean can be beneficial in situations where you have larger outliers in your data, which typically affect the mean very much. -j Virgil Griffith: > Is there some implementation-specific reason not to use the standard > mathematical definition of "median"? If not, I propose changing the > implementation to become it. > > -V > > On Tue, Aug 11, 2015 at 2:44 AM Nick Mathewson <[email protected]> wrote: > >> On Mon, Aug 10, 2015 at 1:11 PM, nusenu <[email protected]> wrote: >>> -----BEGIN PGP SIGNED MESSAGE----- >>> Hash: SHA512 >>> >>> Hi, >>> >>> https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n2028 >>> >>>> If 3 or more authorities provide a Measured= keyword for a router, >>>> the authorities produce a consensus containing a "w" Bandwidth= >>>> keyword equal to the median of the Measured= votes. >>> >>> a random sample from recent votes: >>> >>> grep 37.59.38.117 -A 3 *|grep Measured >>> w Bandwidth=6869 Measured=7570 >>> w Bandwidth=6869 Measured=15500 >>> w Bandwidth=6869 Measured=18100 >>> w Bandwidth=6869 Measured=30500 >>> >>> Tor says the median value is >>> 15500 >>> >>> 2015-08-10-16-00-00-consensus: >>> w Bandwidth=15500 >>> >>> but the median of these 4 values is actually: >>> (18100+15500)/2 = 16800 >>> no? >>> >>> Has tor a different definition of 'median' and simply takes always the >>> second ordered measurement vote out of 4 votes or is there a bug in >>> the spec or implementation? >> >> There's one misplaced throwaway sentence in dir-spec.txt: >> >> " All ties in computing medians are broken in favor of the smaller or >> earlier item. >> " >> >> We should bring this, and probably other things, into a "definitions" >> section earlier in dir-spec.txt. Patches welcome. ;) >> >> -- >> Nick >> _______________________________________________ >> tor-dev mailing list >> [email protected] >> https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev >> > > > > _______________________________________________ > tor-dev mailing list > [email protected] > https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev > _______________________________________________ tor-dev mailing list [email protected] https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev
