''Weighted isolines'' is a method of isoline symbolization in which is
olines vary in width in proportion to the data values they represent.
Results of a map interpretation experiment demonstrate that the weight
ed isolines method is an effective alternative to conventional labeled
isolines of uniform width and 'shadowed'' isolines (which thicken uni
formly along southeastward slopes) for prompting rapid and accurate in
terpretation of statistical surfaces.