A Thesis or a Dissertation is a lengthy piece of academic writing based on research undertaken by the candidate and submitted by them in partial fulfillment of the requirement for an award, usually at the postgraduate level, such as for a Master's degree or a PhD (known also as a Doctorate, or Doctor of Philosophy degree). (Definition developed from A Dictionary of Education, Oxford University Press).
Generally speaking (and especially in the United States), theses and dissertations are completed by students who have already obtained a Bachelor's degree; however, some programs of undergraduate study also include the completion of a Senior Thesis, which may be the capstone of a cumulative research project lasting a semester or more, or is part of the requirements for obtaining an Honors degree from a selective or elite college or university. Here at West Point, some programs of study involve the completion of a Senior Thesis, which, while lengthy, detailed, and based on extensive research (and involving a presentation and defense before a number of faculty members), is not an exact equivalent to a post-graduate thesis or dissertation.
A Master's thesis is intended to demonstrate mastery of available scholarship in a particular field of study. A Doctoral dissertation is generally required to present an original and unique contribution to knowledge in a specific discipline.
(Photo by Sean MacEntee, used through a Creative Commons License http://www.flickr.com/photos/smemon/5613382605/)
Theses and dissertations written for post-graduate degrees are valuable for research because they involve orginal scholarship. That is, the author of the thesis or dissertation must conduct extensive research in a specific discipline, and at the Doctoral level, must perform studies or research that leads to a new conclusion in the selected field of study. For this reason, Doctoral dissertations can be valuable PRIMARY sources for research on a given topic, providing new insights and presenting the research to support those insights.
Remember, PRIMARY sources consist of original research, studies, data, surveys, interviews, documents, reports - newly created items that present original and unique contributions to a field of study, or items that were created at the time of the events you are studying. Thus, original work in the form of a dissertation can provide valuable data and information to support your research.
(Photo by Sean MacEntee, used through a Creative Commons License http://www.flickr.com/photos/smemon/4459776355/)