[en] The method described starts from the requirement that the quantitative statement of a measuring result in dosimetry should contain at least three figures: 1) the measured value or the best estimate of the quantity to be measured, 2) the uncertainty of this value given by a figure, which indicates a certain range around the measured value, and which is strongly linked with 3) a figure for the confidence level of this range, i.e. the probability that the (unknown) correct value is embraced by the given uncertainty range. How the figures 2) and 3) can be obtained and how they should be quoted in calibration certificates is the subject of these lectures. In addition, the means by which the method may be extended on determining the uncertainty of a measurement performed under conditions which deviate from the calibration conditt ions is briefly described. (orig.)