ABSTRACT

Collecting information is one thing, making use of it is another. Because geographical data sets may be very large, some form of numerical summary is usually required if the key features of the data are to be identified and communicated to other researchers. An effective summary usually involves the description of the following five characteristics of the data:

1 the size of the data set (patterns emerging from small data sets are more likely to be idiosyncratic than those emerging in larger data sets);

2 the ‘shape’ of the data (to identify ‘typical’ and extreme values); 3 the central tendency of the data (the tendency for observations to cluster around a

typical value or values); 4 the scatter of the observations about this central, typical value; 5 irregular aspects of the data which cannot be accommodated by characteristics 2 to 4.