It is appropriate to use isarithmic maps for showing spatially discrete variables. Isophletic maps present variables occurring or collected within spatial units such as census tracts. Only absolute values can be shown on isometric maps . A value of a single isoline varies at different locations. Uniformly sized and shaped areas are better for isarithmic maps than irregular ones.
Isobar is a name used for isolines showing magnetic declination.
Densely placed isolines indicate a sharp change of a variable s magnitude in the area. When collecting data more control points should be applied in areas with high fluctuations of data values. Variables should be classified before creating a cartogram. The original shapes and orientation of spatial units is maintained when using contiguous cartogram. As opposed to other mapping techniques, cartograms do not require from the viewer a familiarity with the spatial characteristics of the study area.