19. A system comprising: one or more computers and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising: receiving initial training data, the initial training data comprising initial training records, each initial training record identifying input data as input and a category as output; generating first intermediate training records by inputting input data of a first subset of the initial training records to a first trained predictive model, the first trained predictive model generated using at least a second subset of the initial training records and a training function, each first intermediate training record having a first score; generating second intermediate training records by inputting input data of the second subset of the initial training records to a second trained predictive model, the second trained predictive model generated using the training function and at least the first subset of the initial training records, each second intermediate training record having a second score; and generating, for the first trained predictive model and the second trained predictive model, a score normalization model using a score normalization training function, the first intermediate training records, and the second intermediate training records.
19. A system comprising: one or more computers and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising: receiving initial training data, the initial training data comprising initial training records, each initial training record identifying input data as input and a category as output; generating first intermediate training records by inputting input data of a first subset of the initial training records to a first trained predictive model, the first trained predictive model generated using at least a second subset of the initial training records and a training function, each first intermediate training record having a first score; generating second intermediate training records by inputting input data of the second subset of the initial training records to a second trained predictive model, the second trained predictive model generated using the training function and at least the first subset of the initial training records, each second intermediate training record having a second score; and generating, for the first trained predictive model and the second trained predictive model, a score normalization model using a score normalization training function, the first intermediate training records, and the second intermediate training records. 20. The system of claim 19 , wherein the one or more storage devices further store instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising: dividing the initial training records into subsets of initial training records, the subsets of initial training records including the first subset of the initial training records and the second subset of the initial training records; generating the second trained predictive model using the first subset of the initial training records and at least one other subset of the initial training records of the subsets of training records.