|There are numerous extensions available that
come on-board in ArcView; there are also numerous free (and not free) extensions
that can be added. Here is an example of an extension, Animal Movement
Often, in acquiring real-world data, a point is used to sample a larger region. Thus, one has a scatter of points to represent areal data. One method of regionalization, based on dot scatter, employs the concept of centrality. If the points represent villages, then one who wishes to locate a marketing function might choose some sort of "average" location central among the villages.
Animal Movement extension (find it on the web from Alaska Biological Science Center) offers "spider diagrams" to locate these "average" values. There are three types of "average" value that one can choose: arithmetic mean, geometric mean, and harmonic mean. The first is the largest and the last the smallest. This particular extension allows the user to choose either the arithmetic or harmonic mean or to enter one based on a particular theme. (Use Excel to perform other calculations and then bring in the spreadsheet, if desired.) As an example, if one has ten points in the dot scatter, with lat/long attached (can also be calculated in animal movement), the the arithmetic mean has lat coordinate calculated by adding up the 10 lat values and dividing by 10 (and similarly for long).
Spider diagrams are useful for suggesting regions based on centers. In the absence of regional boundaries, spiders suggest regions. As with dot density maps, there is a scale transformation involved which allows one to get new information through that transformation.