Explainer · Plain-language

What is preregistration in research?

Q: Preregistration means you cannot conduct exploratory analyses.

Preregistration distinguishes confirmatory from exploratory analyses — it does not prohibit exploration. Researchers can and should report both; what preregistration prevents is presenting post-hoc exploratory findings as if they were pre-specified confirmatory hypotheses.

Q: Preregistration guarantees publication.

Standard preregistration on OSF or AsPredicted involves no commitment from any journal. Only a registered report — where a journal issues an in-principle acceptance before data collection — guarantees publication regardless of results.

Q: Preregistration is only relevant to experimental research.

Preregistration is used for observational studies, surveys, secondary data analyses, and systematic reviews (via PROSPERO), not just laboratory experiments. The key requirement is that hypotheses or review questions are documented before the researcher examines the data or literature.

Preregistration is the practice of publicly documenting a study's hypotheses, design, and planned analysis before data collection begins, creating a time-stamped record that allows readers to distinguish between hypotheses that were genuinely confirmatory — specified in advance — and exploratory analyses conducted after viewing the data. It is a central practice in the open science movement and a direct response to concerns about questionable research practices including HARKing and p-hacking.

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The short answer

A preregistration is typically submitted through a public registry such as the Open Science Framework (OSF) or the simpler AsPredicted platform, where it is time-stamped and either immediately public or held under an embargo until publication. For systematic reviews, PROSPERO is the specialist registration platform. A registered report is an extension of preregistration that adds peer review of the protocol before data collection: the journal provisionally accepts the paper based on the preregistered design, guaranteeing publication regardless of the outcome. Preregistration is mandatory for clinical trials under the FDA Amendments Act 2007 (FDAAA) and WHO International Clinical Trials Registry Platform (ICTRP), and is an increasingly expected norm in psychology, social science, and ecology.

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Why preregistration exists: HARKing and p-hacking

Preregistration addresses two related problems in research practice. HARKing — Hypothesising After Results are Known — was described and named by Norbert Kerr in a 1998 paper in Personality and Social Psychology Review, though the practice itself long predates the term. HARKing occurs when researchers generate or reshape their hypotheses after seeing the data but write up and present them as if they had been specified in advance. p-hacking (also called "fishing" or "data dredging") is the practice of selectively running multiple analyses or subgroup comparisons and reporting only those that achieve statistical significance, artificially inflating false-positive rates. Both practices were identified as major contributors to a "replication crisis" in psychology and biomedicine, documented most prominently by the Open Science Collaboration's 2015 study in Science, which found that fewer than half of 100 published psychology experiments replicated successfully. Preregistration limits HARKing and p-hacking by making the original analysis plan public before the researcher can see the results.

Platforms and templates

The Open Science Framework (OSF), operated by the non-profit Center for Open Science, is the most widely used preregistration platform across disciplines. It offers multiple registration templates — including the OSF Preregistration template and the AsPredicted format, which consists of 11 short questions covering the hypotheses, data collection stopping rule, key dependent variables, conditions, analyses, and known data exclusions. AsPredicted.org is a separate platform providing a streamlined preregistration; it is popular in psychology and behavioural economics. Both OSF and AsPredicted assign a DOI to each registration, enabling it to be cited in the registered article. For systematic reviews with health-related outcomes, PROSPERO (operated by the University of York's Centre for Reviews and Dissemination) is the expected platform. For clinical trials, ClinicalTrials.gov (US National Library of Medicine) and the ISRCTN Registry (Springer Nature) are the primary registries.

Registered reports

A registered report is an article format in which a journal peer-reviews the preregistered hypothesis and method before data collection, then offers an in-principle acceptance (IPA) of the paper: the journal commits to publishing the final article regardless of whether the results are positive, null, or negative, provided the authors adhere to the approved protocol. This format, introduced at a small number of journals from around 2013, directly addresses publication bias — the tendency for journals to publish positive results at higher rates than null results. As of 2024, more than 300 journals across disciplines including psychology, neuroscience, ecology, and medicine offer the registered report format. The Centre for Open Science maintains a comprehensive list. Registered reports are distinct from standard preregistration in that the protocol is peer reviewed before data collection and the IPA is a binding commitment.

Funder and journal expectations

Preregistration of clinical trials has been mandatory under US federal law (FDAAA 2007) and WHO ICTRP policy for prospective clinical trials since 2008; journals including ICMJE members have required evidence of registration as a condition of submission since 2005. In experimental psychology and social science, preregistration was an emerging norm by the mid-2010s and is now routine in many areas. The American Psychological Association's ethical principles and many journal author guidelines now either require or strongly recommend preregistration for confirmatory studies. In ecology and evolution, preregistration is gaining adoption; Ecological Applications, American Naturalist, and others now accept registered reports. UKRI does not currently mandate preregistration for all funded research, but its research integrity frameworks encourage it, and the Medical Research Council's Good Research Practice guidelines reference it.

Key facts

At a glance

Definition: Public, time-stamped record of hypotheses and analysis plan created before data collection
HARKing: Hypothesising After Results are Known; named by Kerr (1998, Personality and Social Psychology Review)
Platforms: OSF (Open Science Framework), AsPredicted (11 questions), PROSPERO (systematic reviews), ClinicalTrials.gov (trials)
Registered reports: Journal peer-reviews protocol pre-data and offers in-principle acceptance; 300+ journals now offer the format
Clinical trials: Mandatory under FDAAA 2007 (US) and WHO ICTRP; ICMJE journals require registration since 2005
Replication crisis: OSC (2015, Science) found <50% replication success in 100 psychology experiments — key driver of preregistration norms

Common misconceptions

What people often get wrong

Often heard: Preregistration means you cannot conduct exploratory analyses.

Actually: Preregistration distinguishes confirmatory from exploratory analyses — it does not prohibit exploration. Researchers can and should report both; what preregistration prevents is presenting post-hoc exploratory findings as if they were pre-specified confirmatory hypotheses.

Often heard: Preregistration guarantees publication.

Actually: Standard preregistration on OSF or AsPredicted involves no commitment from any journal. Only a registered report — where a journal issues an in-principle acceptance before data collection — guarantees publication regardless of results.

Often heard: Preregistration is only relevant to experimental research.

Actually: Preregistration is used for observational studies, surveys, secondary data analyses, and systematic reviews (via PROSPERO), not just laboratory experiments. The key requirement is that hypotheses or review questions are documented before the researcher examines the data or literature.

Going deeper