Closed pschloss closed 6 years ago
Thanks for adding the documentation to the README
. I'm afraid this doesn't really answer my questions. What is the difference between elo1_pre
and rating1_pre1
? Also, aside from the numbers inputted to the formulae, is the formula for elo1_prob
different from that of rating_prob1
? i.e. 1/(1+10^((Rb-Ra)/400
@pschloss they explain (at least in words, if not full equations) several of the differences on this blog post. there's some overlap between that post and the README, but I think the post is pretty good for a lot of what you're asking.
for example, the "ratings" are described there as a sort of "decorated" Elo score -- they aren't reverted to the mean like Elo scores, and they are tweaked with overall factors to model some pre-game knowledge (home field advantage, travel distance, and starting pitcher quality).
as for the discrepancies in the calculation of probabilities based on those scores, I suspect they are applying the 24 point home field advantage prior to calculating the probability (that is, the formula would instead be
1 / (1 + 10^((Rb - Ra +/- home_field_advantage_pts) / 400)
this is what they do for nfl elo scores, for example. the numbers are closer in that case (61.3 instead of 61.4) leading me to suspect the home field advantage parameter is not exactly 24
I'm trying to figure out what the column headings mean in the
mlb_elo.csv
file and am running into a problem deciperhing what is in the columns that start withelo*
and therating1_post
andrating2_post
columnsLooking at the data from the 2018-07-01 CHC vs MIN game the csv files has:
The
elo1_pre
andelo2_pre
values don't seem to correspond to what is posted on the website. The pregame ELO scores were 1562 and 1491 (i.e.rating1_pre
andrating2_pre
). I'm not sure where the elo1_pre and elo2_pre came from nor theelo_prob
values (i.e. 1/(1+10^((1491-1562)/400)) = 0.601). Any help?