The race pages calculate a simple score: for every attribute in a race profile, multiply its tendency by the matching class weight, then add the results. Positive overlap raises the score and a penalty on a weighted class attribute lowers it. Attributes absent from a class's extracted weight table contribute zero. The three highest positive results appear as best-fit classes.
This model is useful because it is explainable. Elf scores strongly for Ranger through Marksmanship, Agility, and Reflexes, while its Strength penalty has no listed Ranger weight. Dwarf now scores highest for Warden through Vitality, Armor Use, Resolve, and Parry, with Paladin close behind. Half-Orc scores strongly for Warden through Strength, Power, Aggression, and Vitality while its Spellcraft penalty lands on a class weight of only 0.3.
The score is not a combat simulator. It does not know the final hero roll, wage, traits, age, party synergy, dungeon, or the precise internal effect of every attribute. It also cannot give value to an attribute omitted from the class weight table, even though since 2.12 every one of the thirty attributes does something in a fight and the Ability rating reads all of them. Use it to decide which candidates deserve inspection, never to auto-sign the highest card.