Classification
You may use classification when the data consists of a large group of research objects. You outline and divide the group into classes of objects (sharing similar qualities or resemblances), so you can explain and describe the composition and essence of the group. Variations in classification exist as scientific methods, which obey a degree of logic sliding between exact and imprecise. Examples of classification based on imprecise logic are: principal components analysis, cluster analysis and typologicizing. Since statistical methods are necessary for effective classification, you need to know the basics of both quantitative and qualitative methods of analysis.
Read more on classification from the links below:
Statistical Classification. Wikipedia, The Free Encyclopedia.
Principal Components Analysis. Wikipedia, The Free Encyclopedia.
Cluster Analysis. Wikipedia, The Free Encyclopedia.
What is Cluster Analysis? Electronic Statistics Textbook. Statsoft.