1. A method of predicting a service criterion in a distributed computer network, the method comprising: collecting a set of features about at least one of requests and responses that arrive at an input of the network; collecting a set of data associated with the requests or responses, the data set including at least one of network data and system data; determining a subset of the features which are relevant based upon the collected data set; learning dependencies between features of the subset; specifying a scenario associated with the service criterion of the network, the scenario including one or more conditions; preparing an input distribution, including: filtering the collected data set based on the conditions specified in the scenario, and; executing subsequent requirements in the scenario specification such that the data set is updated to be consistent with both the specified conditions and the dependencies among the subset of features; and outputting a predicted data set for evaluating expected operation of the scenario based on the input distribution.