In the quality control of reinforcement steel bars and wires, several European standards and surveying authorities require periodic quotation not only of the mean level and the dispersion of the mechanical properties, but also of their“characteristic value”, known in theoretical statistics as the lower limit of a statistical tolerance interval. The characteristic value replaces the minimum value, which is considered to be too haphazard and unscientific in nature.Characteristic values can be directly compared only when periodic judgements are based on a constant number of tests, a condition that has been overlooked in all existing standards. If this number is fixed at 100, the characteristic value and the minimum value appear to fall near each other. In addition, the characteristic value is very sensitive to deviations from a normal distribution.