Limitations, Delimitations, and Assumptions in a Thesis or Dissertation

Committees read this section for one thing: whether you understand where your study stops. A researcher who names the boundaries openly is trusted on everything inside them. A researcher who omits them, or lists them carelessly, loses credibility on the rest.

The three terms are often mixed up, and mixing them up is itself a flag. They answer three different questions.

The three terms

Limitations are constraints on your study that you did not choose and cannot fully remove. They come from the circumstances of the research: a sample that was hard to recruit, a response rate lower than planned, reliance on self-reported data, a single institution as the site, or a time period that limited what could be observed.

Delimitations are boundaries you set on purpose. You chose a population, a region, a time frame, a theory, or a method, and in doing so you left other options out. A study of first-generation students at public universities in the Midwest delimits itself to that group. It does not claim to describe private universities or students in other regions, and it chose not to.

Assumptions are conditions you accept as true so that the study can proceed, though you cannot prove them. A common one is that participants answered interview questions truthfully. Another is that a published instrument measures the construct it was designed to measure in your population.

The shortest way to separate them: limitations happen to you, delimitations are your decisions, and assumptions are what you take for granted.

Where they go

Programs differ. Some put all three in Chapter 1, near the end, after the significance of the study. Others place them in Chapter 3 with the design. Some split them, with assumptions and delimitations in Chapter 1 and limitations in Chapter 3 or Chapter 5. Check your program's template and follow it. If the guidelines are silent, ask your chair.

Whatever the location, keep the content consistent. A boundary named in Chapter 1 should not disappear by Chapter 5.

Writing limitations

Naming a weakness is not enough. Each limitation needs three things: what it is, how it could affect the findings, and what you did to reduce the effect.

"The sample was small" gives the committee nothing to evaluate. Compare: "Twelve principals took part, all from public schools in one county. The findings describe their experience in depth, but they cannot be read as representative of principals in other counties or in private schools. To reduce this, the study selected principals from schools of different sizes and distances from the town center, and Chapter 5 limits its claims accordingly." That version states the fact, the consequence, and the response. Our article on justifying a smaller sample size covers the most common limitation in detail.

Keep to limitations that are real. A list of ten generic items, such as "time constraints" and "researcher bias," reads as padding. Choose the few that touch your findings and explain each.

Also avoid listing a flaw so serious that it undermines the study. If a limitation means the research question cannot be answered, it is a design problem and needs a design solution, not a sentence in Chapter 1.

Quantitative studies tend to frame limitations in terms of internal and external validity, such as a non-random sample or a self-report instrument. Qualitative studies tend to frame them around transferability and the researcher's role. Use the vocabulary of your tradition.

Writing delimitations

Each delimitation needs a reason. State the boundary, and then say why you drew it there. "The study includes only teachers with at least three years of experience, because retention decisions among new teachers follow different patterns and require a separate study." The reader should see a decision, not an oversight.

Delimitations also cover what you excluded from the theory or the design, such as why you chose one framework over another or one method over another.

Writing assumptions

State each assumption plainly and, where you can, give a reason it is acceptable. "Participants were assumed to answer truthfully. Confidentiality was guaranteed and participation was voluntary, conditions that support candid responses." Keep the list short and relevant. Do not include assumptions so obvious they add nothing, such as the assumption that participants understood English when the interview was conducted in English.

Keeping the section honest across the dissertation

Return to the boundaries when you write Chapter 5. If you stated that the findings apply to one county, a recommendation addressed to the national education ministry goes further than your design allows. If you named self-report as a limitation, avoid wording in your results that treats reported behavior as observed behavior.

Chapter 3 covers the design these boundaries come from, and Chapter 1 shows where the section often sits.

If you want a structured assessment of whether your design, its limits, and your claims are consistent, our research design and methodology review addresses the concerns most likely to hold up approval. The decisions stay yours.