[Critical questions regarding standard deviation as a precision parameter of blood alcohol determination]

The relative absolute standard deviation, which was introduced for the control of the precision of blood alcohol-determinations by the BGH reveals, that according to technical rules the admissible standard deviation in the range of higher blood alcohol concentrations is exceeded despite the fact, that the width of the variation is still in the acceptable range. The standard deviation of 0.05% should therefore only be applied to the blood alcohol range up to 1.5%. As an alternative the coefficient of variation can be chosen for the precision control.