Abstract: A method and apparatus are disclosed for simplifying and accelerating the measurement of data values associated with subregions of a district or larger region identified by a map, for example. The method relies upon the concept of chain-wise top ographical ordering of the elements to be analyzed, so that each element, except the first or last, has a unique predecessor in the chain. The apparatus of the present invention includes a digitizer and computer, or a resistive evaluating circuit and a resistance measuring apparatus for summing parameter values associated with selected elements.