The best policy modifications are based on large amounts of information that has been gathered through policy evaluation. Evaluation has to be part of the continuous cycle of a bill, it cannot be a one-time look at the implementation of the bill and then assume that the bill will continue to work as it was intended. Prospective policy analysis is completed in the agenda setting stage of bills. It helps identify problems and potential solutions to those problems Policy maintenance is largely a part of legislative oversight and agency control over implemented laws and regulations. His type of analysis is done to help ensure that policies are implemented as they were intended.
Policy monitoring is the measuring and recording of the operation of a policy's implementation.
It is particularly important and pointing out when and where modifications in rules and regulations might be needed. Ex-post policy evaluation is the process through which the real value of a policy is determined. It is usually quite difficult and subjective in nature. It depends on the perceived ideas of whether the bill has been a failure or success.