This part of ISO 11843 specifies basic methods to: – design experiments for the estimation of the critical value of the net state variable, the critical value of the response variable and the minimum detectable value of the net state variable, – estimate the characteristics from experimental data for the cases in which the calibration function is linear and the standard deviation is either constant or linearly related to the net state variable. The methods described in this part of ISO 11843 are applicable to various situations such as checking the existence of a certain substance in a material, the emission of energy from samples or plants, or the geometric change in static systems under distortion. Chritical values can be derived from an actual measurement series so as to assess the unknown states of systems included in the series, whereas the minimum detectable value of the net state variable as a characteristic of the measurement method serves for the selection of appropriate measurement process. In order to characterize a measurement process, a laboratory or the measurement method, the minimum detectable value can be stated if appropriate data are available for each relevant level, i.e. a measurement series, a measurement process, a laboratory or a mesurement method. The minimal detectable values may be different for a measurement series, a measurement process, a laboratory or the measurement method.