This is another difficult question when starting out on a PhD. If you knew the answer to that, then perhaps you would not need to undertake the PhD in the first place. It gets more complicated still (and yet, at the same time, more straightforward!) Obviously, the initial broad area of investigation will get parsed down into a more specific, more manageable topic, with a particular “research question” or perhaps “research problem” which the student then attempts to explore in detail. The PhD, however, is more than simply a research project looking for a clever answer (although, it can be that as well). The most important component of the PhD is to demonstrate that the doctoral candidate fully understands the process of advanced research at this level. In the context of the research project, this means knowing (or learning) when to explore a new area (or branch of academic literature) and when to narrow the options and explore in greater depth. It means learning when to stop reading and start gathering new data; when to start writing and when (and what) to re-visit, edit, and revise. As the student becomes more deeply embedded in the research topic, this becomes more important, because a fondness for the topic might obscure critical judgment, leading to an attempt to have a comprehensive investigation of everything, rather than developing a speciality which advances knowledge about the subject.
Part of this learning process is also about timing. Students frequently complain that they “don’t have enough time” to complete the project successfully, but this is often the case of trying to squash a six-month project into three months. Bad planning means that something has to be sacrificed. It is always difficult to be deterministic about how long it will take to do each stage of a PhD, because each person and each research problem is different. As a rough guide, however, it is not uncommon that over three-years of full-time PhD research, the student will spend the first nine months or so just getting to grips with the literature. During this time they will perhaps complete the draft of a literature review, giving a narrative on the main events and key articles on the research topic to date. Towards the end of this period, the student will be developing a more intimate feel for the methodological approach and the methods of gathering new data that they wish to adopt. The methodology chapter can probably be drafted quite quickly at this point, although it will usually be necessary to revisit it later to ‘tweak’ the proposal to reflect what was actually done! Having established the preferred research methods, ethical permission to conduct the research can now be applied for and hopefully speedily approved.
The PhD now enters the really interesting point – the ‘meat’ in the sandwich – where the student now begins to conduct the research and gather new data. This period (subject to the above caution that every project is different) may last from the end of the first year (of full-time study) until the beginning of the third year. The student will be writing drafts of the results chapter towards the end of this period, and the final six months or so will usually be spent on writing the discussion/conclusions/recommendations chapter and tidying up the dissertation. Do not underestimate how long it will take to check all the spelling, grammar, citations, references, figure numbers, diagrams, and general formatting! A part-time PhD will obviously take longer than the three-year full-time project (normally 5-6 years) but this rough time-line can be adapted to suit. With a clear initial research question, and a careful approach to each subsequent stage in the process, “what you need to know” usually emerges from the academic mist!