Diving Deeper into Limitations and Delimitations
Of course, for this particular example, this does not mean that it wouldn’t be interesting to also know what principals think about the new curriculum. Or parents. Or elementary school children. It just means that, for the purposes of your project and your research questions, you’re interested in the experience of the teachers, so you’re excluding anyone who does not meet those criteria. Having delimitations to your population of interest also means that you won’t be able to answer any questions about the experiences of those other populations; this is ok because those populations are outside of the scope of your project. As interesting as their experiences might be, you can save these questions for another study. That is the part of the beauty of research: there will always be more studies to do, more questions to ask. You don’t have to (and can’t) do it all in one project.
Similarly, the focus of the research problem itself (and the associated research questions) is another common source of delimitations. By choosing to focus your research on a particular problem or question, you are necessarily choosing not to examine other problems or questions. Remember: You can’t answer all possible questions with one project. While this may seem obvious, it’s worth acknowledging. There may be other related problems or questions that are equally worthy of study, but you must choose which one(s) you are and which ones you are not looking into with your project.
Continuing with the previous example, for instance, let’s suppose that the problem you are most interested in addressing is the fact that we know relatively little about elementary school teachers’ experiences of implementing a new curriculum. Perhaps you believe that knowing more about teachers’ experiences could inform their training or help administrators know more about how to support their teachers. If the identified problem is our lack of knowledge about teachers’ experiences, and your research questions focus on better understanding these experiences, that means that you are choosing not to focus on other problems or questions, even those that may seem closely related. For instance, you are not asking how effective the new curriculum is in improving student test scores or graduation rates. You might think that would be a very interesting question, but it will have to wait for another study. In narrowing the focus of your research questions, you limit your ability to answer other questions, and again, that’s ok. These other questions may be interesting and important, but, again, they are beyond the scope of your project.
Common Examples of Limitations
While each study will have its own unique set of limitations, some limitations are more common in quantitative research, and others are more common in qualitative research.
In quantitative research, common limitations include the following:
– Participant dropout
– Small sample size, low power
– Non-representative sample
– Violations of statistical assumptions
– Non-experimental design, lack of manipulation of variables, lack of controls
– Potential confounding variables
– Measures with low (or unknown) reliability or validity
– Limits of an instrument to measure the construct of interest
– Anything else that might limit the study’s internal or external validity
In qualitative research, common limitations include the following:
– Lack of generalizability of findings (not the goal of qualitative research, but still worth mentioning as a limitation)
– Inability to draw causal conclusions (again, not the goal of qualitative research, but still worth mentioning)
– Researcher bias/subjectivity (especially if there is only one coder)
– Limitations in participants’ ability/willingness to share or describe their experiences
– Any factors that might limit the rigor of data collection or analysis procedures
Common Examples of Delimitations
As noted above, the two most common sources of delimitations in both quantitative and qualitative research include the following:
– Inclusion/exclusion criteria (or how you define your population of interest)
– Research questions or problems you’ve chosen to examine
Several other common sources of delimitations include the following:
– Theoretical framework or perspective adopted
– Methodological framework or paradigm chosen (e.g., quantitative, qualitative, or mixed-methods)
– In quantitative research, the variables you’ve chosen to measure or manipulate (as opposed to others)
Whether you’re conducting a quantitative or qualitative study, you will (hopefully!) have chosen your research design because it is well suited to the questions you’re hoping to answer. Because these questions define the boundaries or scope of your project and thus point to its delimitations, your research design itself will also be related to these delimitations.
Questions to Ask Yourself
As you are considering the limitations and delimitations of your project, it can be helpful to ask yourself a few different questions.
Questions to help point out your study’s limitations:
1. If I had an unlimited budget, unlimited amounts of time, access to all possible populations, and the ability to manipulate as many variables as I wanted, how would I design my study differently to be better able to answer the questions I want to answer? (The ways in which your study falls short of this will point to its limitations.)
2. Are there design issues that get in the way of my being able to draw causal conclusions?
3. Are there sampling issues that get in the way of my being able to generalize my findings?
4. Are there issues related to the measures I’m using or the methods I’m using to collect data? Do I have concerns about participants telling the truth or being able to provide accurate responses to my questions?
5. Are there any other factors that might limit my study’s internal or external validity?
Questions that help point out your study’s delimitations:
1. What are my exclusion criteria? Who did I not include in my study, and why did I make this choice?
2. What questions did I choose not to address in my study? (Of course, the possibilities are endless here, but consider related questions that you chose not to address.)
3. In what ways did I narrow the scope of my study in order to hone in on a particular issue or question?
4. What other methodologies did I not use that might have allowed me to answer slightly different questions about the same topic?
How to Write About Limitations and Delimitations
Remember, having limitations and delimitations is not a bad thing. They’re present in even the most rigorous research. The important thing is to be aware of them and to acknowledge how they may impact your findings or the conclusions you can draw.
In fact, writing about them and acknowledging them gives you an opportunity to demonstrate that you can think critically about these aspects of your study and how they impact your findings, even if they were out of your control.
Keep in mind that your study’s limitations will likely point to important directions for future research. Therefore, when you’re getting ready to write about your recommendations for future research in your discussion, remember to refer back to your limitations section!
As you write about your delimitations in particular, remember that they are not weaknesses, and you don’t have to apologize for them. Good, strong research projects have clear boundaries. Also, keep in mind that you are the researcher and you can choose whatever delimitations you want for your study. You’re in control of the delimitations. You just have to be prepared—both in your discussion section and in your dissertation defense itself—to justify the choices you make and acknowledge how these choices impact your findings.