A METHOD FOR ESTIMATING THE QUANTITATIVE RELIABILITY OF ISOLINE MAPS.

A method is presented for estimating the quantitative reliability of isoline maps constructed from observations that vary in space and time. The reliability of isolines is expressed as a variance and equations are developed which relate this variance to observational errors, time errors, positional errors, synopticity errors, primary and secondary interpolation errors, and the space-time rates-of-change and the directions of the gradients of the mapped variable. Equations are also developed for designing a survey whose end product is to be an isoline map of specified variance. These relate the variance to the speeds of travel of the observers, the number of observers the dimensions of the surveyed area, and the type of survey pattern. Four types of survey patterns are illustrated: continuous observations along equi-spaced parallel transects and point observations in aligned rectangular, aligned triangular, and unaligned rectangular patterns.