Defining a close finish

[Rob51852]

Hello everyone

I have a strategy that relies on finding close finishes. Unfortunately I work during the day and cannot access a pc or pictures so am trying to automate it. I have come up with the idea of looking for situations where the last traded price is less than say 2 for 2 horses, 3 for 3 horses etc but that seems overly simplistic. Without giving away any trade secrets is there any other criteria I should add? I already chooses only certain courses

Thank you