More often than not, you will need to focus on a single research limitation, which is not only significant in terms of addressing a flaw in a previous study or reflecting a break from the past, but is significant enough to justify carrying out a piece of dissertation research. When you consider whether the research limitation you are interested in is significant enough, you should ask yourself the following question:
Can I justify the suggestion that the research limitation undermined the ability of the authors to (a) answer their research questions and/or hypotheses and/or (b) defend their findings?
If the answer to either part of this question is YES, there is a strong case to suggest that the research limitation is significant enough to justify your proposed dissertation.
To help you assess whether the flaw you have identified is significant enough, especially when it comes to defending the findings of the journal article you are interested in, start by considering the research design used [see the section on Research Designs if you do not know the difference between research designs]. Briefly speaking, if the research you are critiquing used a quantitative research design, you may want to consider the extent to which the reliability and external validity of the findings were undermined. For research adopting a qualitative research design, you may choose to focus on the relative confirmation, conformability, dependability and transferability of the findings, amongst other things.
If the answer to both parts of the question is NO, it is unlikely that the flaw you are interested in is significant enough to justify taking on a dissertation. For example, the authors of the journal article you are interested in may state that that they had a low response rate, which may indicate that their sample size was lower than they had hoped for. However, it does not necessarily mean that it was so low that it affected the quality of their findings. Sometimes authors will mention if they think this is the case; that is, if a research limitation is a particular problem, but this can be either less common or somewhat hidden in the text. For example, the authors may mention that in future research they would like to extend their research to look at additional relationships between variables or perform types of data analysis that require larger data sets. If you felt that this could have been accomplished within the existing study, perhaps the lower response rate was a significant problem, preventing them from doing this. In such cases, you would need to look at the size of the sample, think about the population being studied, and the research questions being addressed, and make a judgement about this. At the end of the day, it is not a perfect science (if there even is such a thing), so you have to use your judgement.
Just like a flaw in a previous study, a research limitation needs to significant enough to justify a dissertation trying to break from the past. As discussed, one of the more common ways to break from the past is to adopt a different research strategy to the one that was used in the journal article you are interested in. However, simply changing some aspect of the research strategy, whether this is the research paradigm, research design, research methods, data analysis techniques, and so forth, is not enough. You have to be able to justify why you are proposing such a change and how the use of a different approach to your research strategy may have led to a materially different result.
When we use the words materially different result, we mean that you believe a different approach to your research strategy could have changed the outcome of the findings from the original study. Taking the example we used before, this would suggest that adopting a mixed methods research design instead of a quantitative research design could have provided us with a more comprehensive list of options for a given research question. By itself, this may not be significant enough to justify a new study. However, if you felt that such criticisms could be levelled at most of the questions in the survey that was used, there is a much stronger case for conducting new research drawing on a different research design (i.e., a different approach to the original research strategy).
Clearly, ensuring that the research limitation that you are using as a basis for your dissertation topic idea is significant enough is important. However, you also need to ensure that trying to address and overcome this research limitation interests you. Ultimately, you will have to think about this problem and overcoming it for a number of months, so make sure it interests you!
Having established a dissertation idea from a research limitation is an important step. However, if your dissertation topic idea is going to be accepted by your supervisor, you will need to communicate it effectively. To achieve this, you need to turn your dissertation topic idea into a purpose statement.
The purpose statement is the culmination of:
The motivation driving your dissertation;
The significance of the research you plan to carry out; and
The research questions you are going to address.
In this respect, the purpose statement establishes the intent of the whole dissertation [see the article, The purpose statement, for an overview].
At this stage in the article, you should have established:
What research limitation (e.g., a low response rate, an ineffective research design, a poor choice of research methods, etc.) is going to be the motivation driving your dissertation; and
How this research limitation makes your research significant (i.e., it addresses a flaw in a previous study or it reflects a break from the past).
The next stage it to consider how to turn your dissertation topic idea into a number of research questions that you want to address. This is the final step in creating your purpose statement.
In the following section, we look at how you can use future research suggestions, rather than research limitations, as a basis to come up with a dissertation topic idea.