GEG-1 Lecture Notes - Lecture 9: Contour Line, Standard Deviation
Document Summary
Scaling symbols in proportion to the magnitude of the data around a central point. Can be used for actual (city) or conceptual points (center of an enumeration unit, such as counties or states) Can become crowded on maps with small enumeration units. Isarithmic map (contour map) is created by interpolating a set of isolines between sample points of known values (ex: contour map) Isopleth map is a special kind of isarithmic map in which the sample points are associated with enumeration units. Display lines of equal value and they are used to represent continuous surfaces . One dot is set to be equal to a certain amount of phenomena, and ideally the dots are placed where that phenomena are most likely to occur. If you do not have access to ancillary information, such as satellite imagery, it is hard to have confidence in dot placement. Good example of dot mapping- race and ethnicity.
