
BGonline.org Forums
PR xggnusnowiebgblitz
Posted By: Michael Petch
Date: Wednesday, 29 January 2014, at 4:59 a.m.
In Response To: PR xggnusnowiebgblitz (Igor)
Snowie takes the equity lost for a player and divides it by the total number of decisions by both players combined (so literally all moves). GNUBG is more like XG in that it doesn't divide by the total number of decisions by BOTH players combined. XG and GNUBG have slightly different notions of what a trivial play is but the error rate per decision is a players total error divided by the total number of unforced non trivial plays and non trivial cube actions.
XG's error rate per decision (which is of course <= 0) is then multiplied by 500 to get PR.
About a decade ago someone did a comparison of Snowie 4 ERs (The data used was never published and was apparently based on a few hundred matches) that suggested that GNUBG's Error Rate was about 1.4 times higher than Snowie 4's error rate. That was also with the older net so I don't know how much of an impact that would have against GNUBG 1.00+

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