Brower, J.E., Zar, J.H., von Ende, C.N. 1997. Field and laboratory methods for general ecology . Pattern comparison is determining the spatial relationship or association of how different phenomena may interact and form a geographic pattern. The environment is a system composed of many variables. Based on the presence of certain variables we may be able to infer or predict some other variable or association.
Patterns are quite common and form the basis for many assumptions, inferences, and predictions.
For example, the Great Plains of the US tend to have a rectangular road grid system. Certain types of plants tend to grow in certain areas, for example, look at the ecoregions of South Dakota . Is it soil, climate, slope, etc. More often than not, the reason for certain patterns is multivariate. By becoming familiar with the certain methods to measure patterns and their correlation allows one to make more valid assumptions, predictions, and inference.