I have made my own adjustments, which work for me, especially since his book was written so long ago.
I only use finish calls, because I list horses in their running styles on my worksheet.
So my adjustments are halved.
I made a class comparison chart to make the class adjustments easier a faster.
Open $4k stake = $5k Optional and open allowance = $16 starter allowance = $10 claim = $16 Mdn Special = $50k mdn claimers.
The chart levels are 20% up and down.
This allows me to make ratings for foreign races.
Because of the inequality of the purses, I find class more reflective of the quality of the race.
Also, a horse who finishes second in a field of ten has beaten more horses than finishing second in a field of 6 at the same class.
My rating for Tiz a Billy is 71/27-4=23 PCR 309
The rating alone means nothing except to compare to the other horses.
I can make a PCR if a horse has 3 or more races on a surface. If the race is a dirt race I only use dirt races, same for turf. If 3-4 races I put rating in parentheses.
Tiz a Billy shows 10 races, but 2 were dirt races.
In this race the
is 34/11-2.5=8.5 PCR (400) 4 turf races
The
is 77/33-9.5=23.5 PCR 328
And for a non-contender the
is 43/30-3=27 PCR 159
I look at PCR's like a baseball batting average. Who do you want hitting for you?
I handicap with pen and paper, so after I compute the PCR I list form actor ratings, also from Scott's book, and then Hambleton pace ratings giving me a class, form and pace/speed rating to compare the field.
If a horse, or horses is in the top 3 PCR and pace/speed ratings with no form defects has an excellent chance to win. If a forth horse is within 10% of the third horse I will include. I've seen some races where 2/3's can be included.
Today's 8th race 7 horses of 10 are close with one horse only having 2 turf races so should also be included. In these races I rely on form and pace/speed if I play, but usually pass these types of races.
PCR's are almost worthless in maiden races, since most horse don't have enough races to rate. Today's 7th race, only 3 horses have enough races to rate of 14 horses.
And maiden claiming horses have many races to rate, and horse that finish in the money often and don't win can get high ratings where the maiden special drop down will get a low rating, even with the high class minus points, so in these races class rules over PCR.
Just as speed figures shouldn't be absolute, neither should PCR.