[Adjustment and standardization: 2 concepts]

This paper aims at clarifying and distinguishing the notions of adjustment and standardization. These two notions are often ill understood and utilized. Adjustment is conceived as a process of summarizing a set of specific measures. Standardization is conceived as an adjustment to an identical system of weights of two or many sets of specific measures. In the presence of confounding factors, the practice of standardization is essential in order to get valid comparisons between groups. Examples of non adjusted measures, of adjusted but non standardized measures, finally of standardized measures are examined.