If I understand right: (silk_numerator/silk_denominator)+1 = Betfair Forecast Price (decimal). I think it makes sense to change these variables to "silk_forecast", then we don't have to do the extra calculation in our formula. It does not make sense to use "silk_numerator" or "silk_denominator" as a stand alone.I believe the ratings are computed by Timeform and the sum of all forecast prices will be 100%, i.e. no overround included.These forecast prices are also the base for the Betfair reduction factor calculation. Note: Forecast prices (and therefore also reduction factors) might be adjusted during the trading session prior to the off.You can find the Betfair forecast prices at the Betfair site. Select a horse race, then click "Race Card" and after that click "Form/Results".