The title of your dissertation is important, and it requires some thought. You should not spend an inordinate amount of time early on working on that task, rather, you should keep in mind that the title will likely evolve over time. The more you learn about your substantive topic, substantive issue, research methodology, and research design, the more informative you will be able to write your title.
The title may be the only thing a scholar reads when looking for scholarly papers as part of a literature search strategy. It serves in a gate keeping role as part of the decision as to whether the abstract will be read. A colon and semicolon format, which is called a title/subtitle format, is possibly the most common format for scholarly writing, especially the reporting of scientific findings. It certainly is the most informative. The Title generally identifies the substantive topic or issue, and the subtitle generally identifies the methodological approach, or sometimes a hint of the study's findings. There are other combinations of things that can be identified or emphasized in a title/subtitle format, but that approach serves as a nice starting place.
The more information at the onset you can provide your reader about the nature of your study the better. Not only do readers have to make decisions upfront about whether they are going to read your paper, they also make continued reassessments of whether they are going to continue reading your paper, and they use the title to evaluate how the information you are discussing reconciles with their idea of your study purpose, as manifest in the title. Scholars tend to be both curious and skeptical. Such is part of the scientific method. Scholars will not take what you say at face value, rather your words are under constant evaluation and reevaluation, and your title is the first impression you will make on your potential scholarly readers.
Most scholars can get all of these questions answered with varying degree of certainty from that title, though determining the research design and analytic technique from that title would take inference and a knowledge of what the body of science in that area of inquiry finds acceptable and not acceptable for analytic techniques. Do you see the places that might be rewritten over the duration of writing the paper itself? How would you rewrite that title to be more informative?
All said, the more information you can provide your reader in the title about the nature of your study, the better. The more you think about what your title is conveying, the better handle you will have on your research, and the better you will be able to describe it to your reader.