DOT MAPS VS. PROPORTIONAL CIRCLE MAPS: AN ASSESSMENT OF READABILITY, LEGIBILITY AND PREFERENCE

Authors: Z. Mashoka, H.H. Bloemer, and J. Pickles

Bulletin of the Society of University Cartographers (1986) Vol.20, No.2, pp 1-6.

ABSTRACT:  The dot and the proportional circle are two commonly employed cartographic symbols. This paper investigates the READABILITY, LEGIBILITY and PREFERENCE of the two symbols. The results indicate that the graduated circle on maps has characteristics which make it more effective in analyzing and reading numerical information. In general, map readers underestimated the number of dots on maps. Descriptive numerical measurements were applied to evaluate the difference between the estimated  values  and the actual values for each of the tested symbol. The results showed that estimations for the graduated circles (black, used for the test maps, shaded, or open) were closer to the actual values. The estimates for the dot map were farther from the actual values in both the map and non-map contexts.