(introduction...)

Once the question to be answered is clear, the purpose of the costing and the scope of the work have been defined, and it is apparent what alternatives are being costed, the exercise can proceed to describe each alternative in detail. To do this it is useful to be clear about how costs will be classified. To undertake cost analysis of HIV/AIDS prevention, a primary classification by input and organisational level is recommended. It is also useful to make a secondary classification of the strategies by the activities that are taking place within them. This helps ensure that costs are not duplicated or omitted between inputs and activities. It also provides a framework by which a strategy can be costed by activity if this is deemed useful for decision making.