Discrete geographic phenomena are those that have confidentiality limitations. Continuous geographic phenomena are those that last a long time. Long time in geography is defined by the duration of continuous geographic phenomena. Derived variables can be collected directly from ground surveys. Mean of a variable is the value where half of the observations are smaller than this value and half are greater.
Proportion is an outcome of the division of one variable by another.
In the ratio scale the zero value indicates the lack of a variable. Some geographic information is divided into hierarchical classifications . Geometric primitives are spatial objects that are too simple to be represented in the raster format. Fuzzy modelling refers to an incorrect design of cause-effect GIS analysis. When conclusions are drawn about individuals in the area based on non-individual data an ecological fallacy is committed.