Any student writing a dissertation will of course have to begin by choosing a dissertation subject. This initial part of the dissertation process is one the student should give plenty of thought to, as the student will be spending a year or more writing the dissertation. Some of the matters to consider for the dissertation subject are focus, originality, and scope.
A dissertation subject must have the proper amount of focus. Even though the dissertation is a lengthy work, it should focus on a specific topic. The student's goal should be not to cover the entire breadth of a dissertation subject but to become the world's foremost expert in a very narrow aspect of the dissertation subject. For instance, a dissertation subject that lacks focus might be "mating cycles of flies." This dissertation subject would have to be focused. A more appropriate dissertation subject might be "Mating cycles of the drosophila melanogaster in the agricultural Western United States: An outline for non-herbicide-based pest control." This topic is far more specific, and would be suitable for a dissertation subject.
The dissertation subject must be original. The student must be familiar with the body of research that has been done in the field and be able to choose a dissertation subject that has not been covered before. The student's dissertation subject can be similar to an existing dissertation, as long as it handles some different details. If one dissertation on the mating cycle of flies covers pest control in the United States, as above, then another dissertation on the mating cycles of flies might study flies in South America and measure the effects of moisture on population.
The dissertation subject must have the proper scope. While the dissertation subject needs to be focused, it must also contain enough interest to keep the student (and later, the reader) engaged through a lengthy dissertation. To achieve the proper scope, the student can study existing dissertations in the field.
