[What is cost benefit analysis?].
The practical and theoretical bases of cost-benefit analysis are reviewed systematically with particular emphasis on how an analysis can be carried out in practice. A Danish analysis about introduction of vaccination for mumps, measles and German measles is included as a common example. The great significance of elucidating the socio-economical questions to be answered before commencing an analysis is emphasized. It is therefore recommended that, among other things, as a side-effect of the actual cost-benefit analysis, a cash-analysis and a budget analysis should be carried out to identify the parties involved in the immediate expenses and incomes. This is particularly important in the cases where the same parties have a central position in the decision-making processes concerned in the project. In addition, costs and benefits are frequently distributed differently in time in different ways: Short-term expenses and long-term benefits. In connection with decision-making, this may also involve problems and should, therefore, be elucidated in detail. Similarly, the importance of including many alternatives in the analysis is emphasized and illustrated. In conclusion, it is demonstrated how well the theoretical principles have been followed, the employment and the process which led to the concrete analysis.