Listy Biometryczne-Biometrical Letters Vol.36(1), 1999, pp.31-36
Chemical elements, like heavy metals, which occur in soils as a result of environment contamination, take different forms, called fractions. To determine the structure of contamination, a sequential chemical extraction is applied. In that way the researcher can determine the total content of the searched element as well the contents of all its particular fractions. Since the whole process is expensive and time consuming, the total number of measurements is confined. Under these assumptions, we indicate the optimal plans of determination of fractions with regard to the precision of the results obtained.
A-optimality; D-optimality; best linear unbiased estimator