Should Local Theses and Dissertations Be Included?

Do local theses and dissertations belong in your evidence base?

You search for research on a highly local topic and find surprisingly few journal articles. Then a university repository reveals dozens of master's theses and doctoral dissertations on related populations, institutions, programmes, and problems.

Should these be included? Excluding them may remove locally relevant research that never reached journal publication. Including them indiscriminately can create another problem: a thesis may not satisfy your research question, study-design requirements, or methodological standards simply because it is the only local evidence available.

The decision should therefore be based on what kind of evidence your study requires, not on a blanket rule that theses are either inferior or indispensable.

Include theses and dissertations when they meet your eligibility criteria

Theses and dissertations are evidence sources, not a separate standard of evidence

Why theses and dissertations matter in comprehensive searching

Theses and dissertations are commonly treated as a category of grey literature. Current Cochrane guidance identifies dissertations and theses among the grey-literature sources that review authors should consider when seeking a comprehensive evidence base. One important reason is publication bias.

Research findings do not all have the same probability of reaching journal publication. Studies with statistically significant, positive, or otherwise attractive findings may be more likely to be published than studies with null or inconclusive results. Searching academic work that did not proceed to journal publication can therefore help reduce dependence on the published journal record alone.

This does not mean that every dissertation search will materially change a review. The likely value depends on the field, question, period, and availability of unpublished academic research.

Local topics can make theses particularly valuable

For highly localized questions, graduate research may document populations and settings that rarely appear in internationally indexed journals. Universities routinely supervise research in nearby schools, hospitals, communities, businesses, ecosystems, and government agencies. Some of that work remains only in institutional repositories or university libraries.

A search that depends exclusively on international indexing can therefore underrepresent the local research record. This is one reason researchers looking for local studies outside international databases may need to search institutional repositories directly.

Do not equate a thesis with one particular level of quality

“Thesis” or “dissertation” describes an academic document and its role in a degree programme. It does not tell you, on its own, whether the underlying study is methodologically strong.

Some dissertations contain substantial original research with detailed methods, extensive appendices, and more procedural information than a compressed journal article. Others have serious design, measurement, sampling, analysis, or reporting limitations. The same broad variability exists within journal literature.

Appraise the study according to its design and your research question rather than using publication format as a shortcut for quality.

Decide eligibility before seeing whether the local evidence is convenient

If theses and dissertations are eligible evidence for your review, that decision should ideally be made in the protocol or search plan before you know whether they support the argument you hope to make.

For example, excluding dissertations because they are “unpublished” after discovering that their findings conflict with journal articles would introduce an obvious risk of selective inclusion. Conversely, relaxing your eligibility criteria solely because a thesis is the only study conducted in your locality can make the review inconsistent.

A dissertation and a journal article may be two reports of one study

A common complication is subsequent publication. A doctoral dissertation may later produce one or several journal articles. A master's thesis may become a conference paper and then an article. Counting each document as an independent study would artificially increase the apparent amount of evidence.

Cochrane guidance emphasizes that systematic reviews should treat the underlying study, rather than individual reports, as the unit of interest. When multiple reports describe the same study, they should be linked and considered together.

Compare authors, sample sizes, participant characteristics, recruitment dates, locations, interventions, measures, and results. The thesis may provide methodological details omitted from the article, while the article may contain later analyses or corrections. Neither document necessarily has to be discarded simply because both exist.

Search beyond the title and abstract when necessary

Thesis metadata can be inconsistent. Some repositories provide detailed abstracts and subject terms; others offer only basic bibliographic information. A study's local setting may appear in the methodology rather than the title.

Use variations of the topic, population, institution, geographic area, and relevant local terminology. When repository search functions are weak, shorter queries often work better than elaborate Boolean strings.

Once a useful thesis is found, inspect its references, author information, department, supervisor, and institutional collection. These details can expose other locally relevant work.

Use thesis databases and institutional repositories together

No single thesis source provides universal coverage. Depending on your setting, useful sources may include national thesis services, commercial dissertation databases, institutional repositories, university library catalogues, and repository directories.

For example, the British Library's EThOS service provides metadata for more than 650,000 UK doctoral theses and links, where possible, to copies held in university repositories. Coverage structures differ elsewhere, so researchers should identify the systems appropriate to the country or institutions relevant to their question.

For highly local research, direct repository searching can be particularly important because institutional collections may contain material not exposed consistently through broader discovery systems.

Do not confuse peer examination with journal peer review

A thesis or dissertation has normally passed through institutional academic processes appropriate to its degree, but those processes differ among universities and programmes. Examination of a dissertation is not identical to journal peer review, and neither process guarantees that a study is correct.

Instead of trying to assign a universal prestige hierarchy, examine the information relevant to the study's credibility: research design, sampling, measurement, analytic methods, transparency, consistency of reporting, and limitations.

Theses may contain more methodological detail, but that creates work too

One advantage of dissertations is space. A dissertation may report instrument development, recruitment procedures, coding frameworks, sensitivity analyses, appendices, and other details omitted from a journal article because of word limits.

The trade-off is practical. Dissertations can be hundreds of pages long, terminology may be idiosyncratic, reporting structures vary, and extracting comparable data may take considerably longer than extracting data from standardized journal reports.

Search comprehensively only when your review requires it

The appropriate search effort depends on what you are producing. A systematic review seeking all eligible studies has a stronger reason to search relevant dissertations than a brief narrative overview whose purpose is simply to introduce an established concept.

Current Cochrane guidance describes searching relevant grey literature sources such as dissertations and theses as highly desirable for intervention reviews because searches should be as extensive as possible where comprehensive identification of studies is required.

That principle should not be transformed into a universal rule for every literature review. Match the search to the purpose, and explain the boundaries you choose.

How local theses can change the picture without automatically changing the conclusion

The value of searching theses was not that every retrieved document became evidence. It was that potentially relevant studies were given a fair opportunity to meet the same substantive criteria as research discovered elsewhere.

Common mistakes when using theses and dissertations

Decide whether theses belong in the search before deciding what their findings mean

Including theses should therefore be a methodological decision rather than an act of generosity toward local scholarship. Search them because they may contain eligible evidence that other channels miss. Evaluate them because local relevance and methodological credibility are separate questions.

Where reporting is weaker than in the international journal literature, the next issue is how to evaluate locally relevant evidence without confusing incomplete reporting with either automatic exclusion or automatic credibility.

Before including local theses and dissertations

Questions about local theses and dissertations

Search theses for missing evidence, then judge the studies on their merits

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