A dissertation is a subject you chose for yourself. The first usage of the word in the English language in 1651 also gives a useful starting definition: “an extended written treatment of a subject”.
Another useful clue is found in the Latin origin of the word – dissertation comes from a Latin word ‘dissertare’ = ‘to debate’.
The masters thesis and doctoral dissertation are written documents that describe the graduate student’s research. The subject of the thesis/dissertation is chosen by mutual agreement between the student and major adviser, and must be approved by the student’s Supervisory Committee. There is no fixed length for the thesis/dissertation, although the Supervisory Committee should provide guidance on format and content.
Masters theses should reveal a capacity to carry on independent study or research and should demonstrate the student’s ability to use the techniques employed in their field of investigation. Doctoral dissertations should demonstrate technical mastery of the student’s field and advance or modify current knowledge. Dissertations should treat new material, find new results, or draw new conclusions; or it should interpret old material in a new light. It is expected that the research contained in the thesis/dissertation will be worthy of publication in appropriate peer-reviewed journals. Students are expected to prepare the manuscript(s) for publication prior to, or soon after, completion of their graduate program.