1. A system comprising: one or more processors; and a memory storing instructions, when executed by the one or more processor, to provide: an analysis engine operable to compare one or more actual output work items generated by participants of an actual business process representing a business policy to one or more modeled output work items from one or more modeled business controls representing the business policy and to report differences between the one or more actual output work items and the one or more modeled output work items indicating how closely the actual business process adheres to the business policy, wherein: each actual output work item includes one or more actual output data values, the actual business process changing an actual input work item into the actual output work item; each modeled output work item includes one or more modeled output data values, the one or more modeled business controls executing on one or more modeled input work items and generating the one or more modeled output work items; input data values included in each modeled input work item are determined from one of matching (1) corresponding values included in a corresponding actual input work item and (2) the corresponding actual output work item; each modeled business control is defined by a set of business rules that represent the business policy, the analysis engine being operable to use the set of business rules to generate the one or more modeled output work items using the input data values of the one or more modeled input work items; responsive to determining that one of the one or more actual output work items differs from a corresponding modeled output work item, the analysis engine creates a rule audit trail for identifying a root cause of a discrepant work item by analyzing the last business rule from the set of business rules that have been used to generate the corresponding modeled output work item, the discrepant work item indicating a difference between the one of the one or more actual output work items and the corresponding modeled output work item, the root cause including a business rule from the set of business rules, the root cause: having input data values matching to the corresponding values included in the one of the one or more actual input work items; having modeled output data values that are different from the corresponding values in the one of the one or more actual output work items; and indicating that the discrepant work item is caused by one of: an incorrect execution of the business policy; and an incorrectness in the business policy.