The STROBE Statement, short for Strengthening the Reporting of Observational Studies in Epidemiology, is a reporting guideline that specifies the information an observational study should include so that readers can judge its validity and reuse its findings. STROBE is a checklist for authors, reviewers and editors; it does not dictate how a study should be designed or analysed, only what must be reported transparently once the work is done.
Observational studies make up a large share of epidemiological evidence, yet they cannot randomise who is exposed to what. Their credibility therefore rests unusually heavily on the clarity of their reporting, and STROBE exists to make that clarity a shared, citable expectation rather than a matter of individual habit.
What STROBE covers
The STROBE checklist enumerates items spanning the standard sections of a research paper: title and abstract, introduction, methods, results and discussion. The methods items are central, asking authors to describe the study setting, eligibility criteria, the variables and how they were measured, the data sources, efforts to address potential sources of bias, how the study size was determined, how confounding was handled, and the statistical methods used. The results items ask for the flow of participants through the study, descriptive data on the participants, and the main estimates reported with measures of uncertainty such as confidence intervals. Several items deal specifically with how the study handled missing data, how continuous variables were grouped or modelled, and whether any sensitivity analyses were performed, because each of these choices can materially change a result and each is easy to leave undescribed. A short, structured abstract is also expected, so that readers scanning the literature can grasp the design, population and main findings before reading the full text.
The aim is completeness rather than a particular conclusion. When every relevant item is reported, a reader can assess whether the conclusions are supported by the design and data, and another team can attempt to reproduce the work or pool it in a synthesis. This emphasis on transparent, reusable reporting aligns directly with the wider goals of reproducibility in research, where undocumented methods are a primary obstacle to replication.
Three observational study designs
STROBE is written to cover the three principal observational designs, with a common core checklist plus design-specific guidance where the designs diverge.
| Design | How it observes | Typical question |
|---|---|---|
| Cohort | Follows groups over time by exposure status | What outcomes follow an exposure? |
| Case-control | Compares exposure histories of cases and controls | What exposures preceded an outcome? |
| Cross-sectional | Measures exposure and outcome at one point | What is associated at a given time? |
Because these designs differ in how data are gathered and in the biases they are prone to, certain checklist items are tailored to each. A case-control study, for example, must report carefully how cases and controls were selected, while a cohort study must report how participants were followed and how losses to follow-up were handled. Reporting which design was used, and reporting it accurately, is itself a STROBE requirement and a prerequisite for sound interpretation, since the same association means different things under different designs.
Extensions and related reporting tools
The core STROBE checklist has been supplemented by extensions that address particular fields and data types while keeping the same philosophy of transparent reporting. These extensions adapt the checklist for areas such as molecular and genetic epidemiology, nutritional epidemiology, infectious-disease studies and research that reuses routinely collected health data, where additional reporting items are needed to let readers judge validity. The proliferation of extensions reflects a general principle: the more specialised or complex the data source, the more there is to report before a study can be appraised or reproduced. Authors should check whether an extension exists for their study type, because using the most specific applicable guideline captures reporting items that the generic checklist would miss. This mirrors the broader move in research toward documenting not just results but the full provenance of the data and analysis behind them.
STROBE and the EQUATOR Network
STROBE is one of the most widely used guidelines hosted by the EQUATOR Network, an international initiative that curates reporting guidelines to improve the reliability and value of the health research literature. EQUATOR organises guidelines by study type, so STROBE sits alongside guidelines such as CONSORT for randomised trials and PRISMA for systematic reviews. Locating a guideline through EQUATOR helps authors choose the correct checklist for their study type rather than reaching for a familiar but inappropriate one.
Within an evidence ecosystem, having a named, citable reporting standard makes expectations explicit for everyone involved. It also connects observational studies to the population measures they rely on, such as incidence and prevalence and the denominators drawn from a census. Consistent terminology drawn from the CASRAI dictionary further helps keep the language of reporting stable across studies and journals.
How STROBE is used in practice
In practice, STROBE is most useful when it is consulted at the writing stage and again at peer review. Authors typically complete the checklist and indicate, for each item, the page or section where it is addressed, submitting this alongside the manuscript so that editors and reviewers can verify coverage quickly. Many journals reference STROBE in their instructions to authors for observational research, which gives the guideline practical force rather than leaving it as an optional ideal. Importantly, STROBE is not a quality score: a study can be reported completely yet still have design limitations, and conversely a strong study reported poorly is hard to trust. The checklist’s role is to ensure that whatever the study did, the reader can see it clearly. Used this way, it improves the appraisal, synthesis and reuse of observational evidence without constraining how researchers choose to investigate their questions.
Why transparent reporting matters
Observational studies cannot randomise exposure, so their credibility rests heavily on how clearly the methods, data sources and analytical choices are reported. Incomplete reporting makes it impossible to judge whether bias or confounding could explain the findings, and it makes the work difficult or impossible to reproduce, which weakens the cumulative evidence base. Transparent, STROBE-compliant reporting supports critical appraisal by readers, enables evidence synthesis by reviewers, and allows secondary analysts to reuse the work with confidence. Authors preparing observational manuscripts can consult the guidance for authors to align their reporting with these expectations from the outset rather than retrofitting it at submission.
Frequently asked questions
Is STROBE a way to design a study?
No. STROBE is a reporting guideline, not a design or analysis protocol. It tells authors what to report so readers can evaluate the work; the design and statistical choices remain the researchers’ responsibility and are made before STROBE applies.
Which studies should use STROBE?
STROBE applies to observational designs, specifically cohort, case-control and cross-sectional studies. Randomised trials, systematic reviews and other study types have their own guidelines, which can be located through the EQUATOR Network’s catalogue.
How does STROBE relate to reproducibility?
Complete, transparent reporting is a precondition for reproducibility. By prompting authors to describe data sources, variables, bias and methods fully, STROBE makes it possible for others to appraise, synthesise and attempt to replicate observational findings.
