The analysis of patent information can mean a number of different things, as can the concept of patent mapping. The type of map that is created depends upon the question that is trying to be answered. From my understanding, this analysis can be divided into two broad categories.
Data mining involves the extraction of fielded data and the analysis thereof.
An example would be if someone wanted to examine the relationship between patent assignees and International Patent Classification codes for a specific area of technology. Mining or mapping this information can give someone an idea of who are the major players in a technology area and what type of work they are generally focusing on. When using Derwent data, a similar analysis can be done replacing IPC codes with Derwent manual codes. Text mining or mapping typically involves clustering or categorizing documents based on the major concepts that are contained within. The data source is unstructured text data, it is not fielded and the only structure is that which the author has applied when they wrote the document and built relationships between different concepts within.