Originally Posted by samagon
I fell victim to one of the classic blunders - The most famous of which is "never get involved in a land war in Asia" - and slightly less well-known is: "Never go against a Sicilian when death is on the line" - but even more slightly less well known is this: "never calculate arithmetic mean when you should be calculating harmonic mean"
What I don't get though, is why is harmonic mean more appropriate than typical arithmetic in this case. Using harmonic just guarantees a lower than what should be expected average. All it does is make the estimate more conservative in terms of the MPG model...