The dissertation represents the culmination and comprehensive application of the knowledge and skills a student has acquired in graduate school. Prospective PhD candidates will hamper their efforts by trying to tackle a wholly unfamiliar subject or begin work outside their specialization or chosen sub-discipline. Candidates will save time by seeing the dissertation as an extension of already completed research. For instance, a student who has already helped coordinate a dig in Tunisia could use the dissertation project to analyze the findings. Students who have studied a particular dialect can expand their existing research into how this dialect has changed over time or in response to migrations or political upheavals.
Candidates who are stuck on a topic can ask their dissertation committee chairperson for suggestions; the chair might know of persistent or unexplored questions or issues in the field that require further study. The chair must approve the topic selected, and will often suggest or even demand modifications to the topic and research methods and analysis.
Doctoral students can find topics by analyzing the current trends in their sub-discipline to see if any of their completed research dovetails with relevant interests. Current trends will appear in recent articles published by the more prestigious journals in the field, such as "Human Organization" for cultural anthropology and "Science" for biological anthropology.
A successful dissertation must contribute new knowledge to the field of anthropology and will not achieve this goal by addressing topics that other anthropologists have thoroughly covered. In many cases, a dissertation will introduce a new researcher to the field. This point does not imply that candidates should choose a trendy or controversial subject; however, it does entail that a dissertation or summary of the research will act as an introduction to the candidate's work, abilities and interests. The dissertation may also lead to a teaching or research position; university departments and institutes select candidates in part on how well the prospective employees past research coincides with the research interests of the employer.
Good dissertation projects are specific in focus while also enabling the candidate to amass and analyze enough research for a book-length work. For example, a recent successful dissertation at Princeton University analyzed recent developments in the culture of Brazil concerning beauty and cosmetics. A good dissertation project topic will also provide a clear and comprehensive subject. For instance, another recent Princeton dissertation focused on the development of rural methamphetamine manufacturers and dealers as a specific criminal class.