Elo ratings calculations - why is home advantage 100 points

[Vilamoura04]

In the traditional Elo ratings calculations it is generally accepted that the home team gets a 'boost' of 100 points to account for home advantage. Why 100 points? Is this based on anything? A round 100 sounds more than a little bit arbitrary to me. Why not 80 points or 120 points? I have read papers where authors suggest 85 points is more accurate for a MLS Elo system, which I assume reduces the home advantage a team gets. Which is strange because the ML tends to have a big home advantage. Is there a way that this number could be calculated, as there are big discrepancies between countries and divisions in countries as to how much of an advantage playing at home gives.

[a1ehouse]

Re: Elo ratings calculations - why is home advantage 100 points I calculated that there were substantial differences between leagues and countries when I developed my ratings. Previously I used 100 for all home team advantage, but tried to tighten the model using division-specific points advantage. See here for details: http://www.punterslounge.com/forum/f21/elo-access-function-75510/#post1457007