A bottom-up strategy assumes you are designing a topic from the individual evidence topics up through the top-level topics which will be defined. With this strategy, your topic design objective is to select documents containing information similar to your lower-level topics.
When you use a bottom-up design, you can start with a document which contains a good representative sample of the words or phrases you want to search for. Then you can group these words by successively higher classifications.
A bottom-up design works best when you have documents which are representative of many other documents that contain similar information. This approach is also useful when your information sources are not subject to many changes or additions.
Keep in mind that topic designs based on the contents of specific documents may miss related subject areas in other documents. For example, if a name is used in the sample document and that name changes in other documents, the new name may be missed in searches.
In addition, the bottom-up strategy implies that your topic design is tuned to the specific document set being used to develop
your topics. These documents may not be representative of all documents contained in your information sources. So, you should
periodically review the effectiveness of your searches.