Rule #36: Avoid feedback loops with positional features.The position of content dramatically affects how likely the user is to interact with it. If you put anapp in the first position it will be clicked more often, and you will be convinced it is more likely tobe clicked. One way to deal with this is to add positional features, i.e. features about the positionof the content in the page. You train your model with positional features, and it learns to weight,for example, the feature "1st­position" heavily. Your model thus gives less weight to other factorsfor examples with "1st­position=true". Then at serving you don't give any instances thepositional feature, or you give them all the same default feature, because you are scoringcandidates before you have decided the order in which to display them.