Delimitations, assumptions and limitations in a dissertation describe the edges of your study: what you chose to leave out, what you accepted without testing and what weakened the design despite your efforts.
Committees read these sections closely because they reveal how well you understand your own study. This guide shows how to separate the three, with examples for quantitative, qualitative and DNP projects.
The Difference in One Line Each
Delimitations are boundaries you set on purpose, such as population, setting or timeframe. Assumptions are conditions you accept as true without testing, such as honest survey responses. Limitations are weaknesses outside your full control that constrain what the findings can claim, such as a convenience sample.
Each needs a reason. A delimitation needs a justification, an assumption needs a basis and a limitation needs an account of its effect and what you did to reduce it.
The Three Concepts at a Glance
| Delimitations | Assumptions | Limitations | |
|---|---|---|---|
| Who controls it? | You, by choice | Nobody fully; you accept it | Largely outside your control |
| When decided? | During design | During design | Identified in design, confirmed after data collection |
| What it does | Narrows scope | Underpins the method | Constrains interpretation |
| What you must add | Why this boundary | Why it is reasonable | Its likely effect and mitigation |
| Typical location | Chapter 1 | Chapter 1 or 3 | Chapter 1 or 3, revisited in Chapter 5 |
Delimitations: Boundaries You Choose
Every study excludes far more than it includes. Delimitations make the most consequential exclusions explicit so a reader knows the study's intended scope.
Common delimitations cover the population, the setting, the timeframe, the variables or constructs examined and the theoretical lens. The justification matters more than the list: the reader wants to see that the boundary serves the research question.
Example delimitation. "This study is delimited to first-year secondary teachers in public schools in one state. Early-career teachers were chosen because attrition is highest in the first year, and a single state was chosen so that certification requirements and induction policy are held constant."
Note that this is not an apology. A delimitation is a design decision you defend, not a weakness you confess.
Assumptions: What You Accept Without Testing
Every method rests on conditions the researcher cannot fully verify. Naming them shows you know what your conclusions depend on.
- Methodological: participants answered honestly; the instrument measures the construct it claims to.
- Philosophical: the paradigm's stance, such as realities being socially constructed in an interpretivist study.
- Statistical: the test's assumptions, such as normality or independence of observations.
Statistical assumptions are a special case: you should test them in Chapter 4 rather than simply assume them. List them in Chapter 1 or 3 only if your program template asks you to.
Example assumption. "It is assumed that participants answered the burnout inventory honestly. Anonymity was guaranteed and no identifying data were collected, which reduces the incentive for socially desirable responses."
A good assumption statement gives its basis. Without one, the assumption reads as wishful thinking.
Limitations: Weaknesses You Cannot Fully Control
Limitations are features of the design or circumstances that restrict what you can conclude. Writing them well is a sign of maturity, not weakness.
For each limitation, state what it is, how it might affect the findings and what you did to reduce its impact. Then stop. Over-apologizing suggests you doubt your own study.
Example limitation. "Recruitment relied on a convenience sample from professional association mailing lists, so teachers who are less engaged with their profession may be under-represented. This could inflate reported commitment scores. Demographic data were compared with state workforce figures to show how far the sample resembles the wider population."
Telling Them Apart: Quick Tests
Students often mislabel a delimitation as a limitation, or the reverse. Three questions sort most cases.
- Did I choose it? If yes, it is a delimitation.
- Am I taking it on trust because it cannot reasonably be tested? If yes, it is an assumption.
- Does it weaken my ability to generalize or infer causation, despite my choices? If yes, it is a limitation.
Some features are both. Choosing a single site is a delimitation; the resulting limit on generalisability is a limitation. Write the choice in one place and its consequence in the other, and cross-refer rather than repeating yourself.
Examples by Study Type
| Study type | Delimitation | Assumption | Limitation |
|---|---|---|---|
| Quantitative survey | Registered nurses in acute care only | The validated scale measures burnout as intended | Cross-sectional design cannot show causation |
| Qualitative interviews | Parents of children diagnosed in the past two years | Participants can articulate their experience | Findings reflect one regional health system |
| DNP quality improvement project | One 30-bed unit over 12 weeks | Chart documentation reflects care delivered | No control group, so secular trends cannot be excluded |
| Mixed methods | Two community colleges in one district | Survey and interview data address the same construct | Small qualitative strand limits integration |
DNP projects in particular are often single-site, short and uncontrolled by design. Name these features plainly; reviewers know the constraints of practice-based projects and respect honest framing.
Where They Go and How Long They Should Be
Placement varies by program. Many US dissertation templates put all three in Chapter 1, often under a "Scope" or "Nature of the study" heading. Others move limitations to Chapter 3 or the end of Chapter 5. UK theses rarely use a separate assumptions heading at all.
Follow your template. If it is silent, a common arrangement is delimitations and assumptions in Chapter 1, anticipated limitations in Chapter 3, and a full limitations discussion in the final chapter once you know how the study actually unfolded.
Length should be proportionate. A paragraph per item, with three to five items in each category, is typical. A two-page limitations section in a proposal usually signals over-apology.
Writing Each Section Clearly
Clear, consistent phrasing helps the reader see which category each statement belongs to. These patterns are starting points; adapt them to your study and your discipline's conventions.
| Section | Pattern |
|---|---|
| Delimitation | "This study is limited in scope to [boundary] because [reason linked to the research question]." |
| Assumption | "It is assumed that [condition]. This is reasonable because [basis], and [step taken] supports it." |
| Limitation | "[Feature] may [effect on findings]. To reduce this, [mitigation]; nonetheless, findings should be read as [appropriate caution]." |
Write in the future tense in a proposal ("the study will be delimited to...") and switch to the past tense in the final dissertation. That small change is one of the most commonly missed edits when a proposal becomes Chapter 1.
Avoid absolute claims in either direction. "This limitation invalidates nothing" sounds defensive, and "these results cannot be trusted" undermines your own work.
How Committees Read These Sections
Committee members use these sections to test whether you understand the trade-offs in your design. They look for consistency more than length.
- Do the delimitations match the population and setting described in Chapter 3?
- Are the assumptions consistent with the paradigm and method?
- Are the limitations ones the design genuinely has, rather than a stock list?
- Does the discussion chapter return to the limitations when interpreting results?
Common Mistakes
| Mistake | Fix |
|---|---|
| Calling deliberate choices limitations | Move them to delimitations and justify them |
| Stock limitations copied from other studies | Name the weaknesses your design actually has |
| Assumptions with no basis | Say why each is reasonable |
| Limitations with no effect stated | Explain how each might bias or restrict findings |
| Ignoring limitations in the discussion | Use them to temper interpretation and suggest future research |
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Frequently Asked Questions
Delimitations are boundaries you deliberately set, such as population or timeframe. Limitations are weaknesses largely outside your control that restrict what the findings can claim.
No. Many US doctoral templates include one, while many UK and other programs do not. Follow your program's template and your chair's guidance.
There is no fixed number. Three to five genuine limitations, each explained with its effect and mitigation, is common. Quality matters more than count.
Not quite. Statistical assumptions, such as normality, should be tested and reported in your results. Research assumptions, such as honest responses, cannot be fully tested and are stated with a rationale.
Yes, as anticipated limitations, usually in Chapter 1 or 3. You then revisit them in the final chapter once you know how the study actually unfolded.
The choice is a delimitation and its consequence may be a limitation. For example, choosing one hospital is a delimitation, and the resulting limit on generalisability is a limitation.
Yes, but they should be judged on qualitative terms, such as transferability and researcher influence, rather than on sample size or statistical generalisability.