According to Perrin the indicators relating to the costs are mainly to be classified among the results’ indicators [1]. The two criteria considered are on one side the cost of the product and on the other side the respect of the budget:
- the respect of the product cost is proposed within the framework of the development of the target costing methods (management by cost-target) and ABC (Activity Based Costing). The idea is to fix a target cost as an objective to which one must make correspond the cost of the product. The indicator then used, is the relationship between the effective and the objective product cost,
- the respect of the budgets, in particular of the studies’ budgets, is the second element to be taken into account at the financial level. The indicator is then naturally the ratio between the exceeding and the initially fixed budget.
The contextual industrial evolutions change the nature of the costs in the company. Formerly, the final costs included a large majority of direct costs (often about 70%), i.e. directly assigned to the products (labour or raw material). The other costs could be the subject of global distributions; the choice of the scale hardly influenced the result. The method of the cost accounting with indirect expenses shared through a fixed percentage, can be admitted as long as their proportion is not too big. But the proportions are reversed, the direct costs do not constitute often any more that 30 % of the total cost. Not only the indirect expenses, according to odd sharing keys, create an arbitrary factor in the calculation of the costs, but it make the control difficult. These two concerns gave place to many researches that ended up in deeply modifying the systems
of costs evaluation.