An analytic system may have a number of processing stages. One or more data sources may provide data to a first processing stage. The first processing stage may specify one or more data contracts having a schema describing a layout and types of data provided by the one or more data sources. Each of the processing stages may specify a respective data contract having a schema such that the processing stages may understand a layout and types of data provided as input to the processing stages. The data contracts me further specify a valid range of values for various items of data described by schemas. Data not conforming to a data contract may be automatically filtered out such that a corresponding processing stage may not be provided with the non-conforming data.