API is a great indication of the class of a horse and if you concentrate on the top 5 API runners you have a good chance of getting the winner....the only problem is that API is for the horses career so if you have a horse that won some really big races as a 2 and 3 year old but is now 5 and not winning these figures can be distorted also this includes the many race bonuses that they have in VIC and QLD so so a horse with a high API may not be the class runner if they have won a lot of races with bonuses....a lot of people on here will tell you it is better to say take the horses last 10 starts prize money winnings and devide that by 10 the give you a more current API you could use less starts if you wish....if you don't have access to that many starts or the form you have is limited use the API on that site or in many racing papers it is a great place to start your form selections.