preregistration (science) preregistration (science) preregistration is the practice of registering the hypotheses, methods, and/or analyses of a scientific study before it is conducted. clinical trial registration is similar, although it may not require the registration of a study's analysis protocol. finally, registered reports include the peer review and in principle acceptance of a study protocol prior to data collection. clinical trial transparency, a 2017 policy guide, argues for registration preregistration assists in the identification and/or reduction of a variety of potentially problematic research practices, including p-hacking, publication bias, data dredging, inappropriate forms of post hoc analysis, and (relatedly) harking. it has recently gained prominence in the open science community as a potential solution to some of the issues that are thought to underlie the replication crisis. however, critics have argued that it may not be necessary when other open science practices are implemented such as registered reports. types standard preregistration in the standard preregistration format, researchers prepare a research protocol document prior to conducting their research. ideally, this document indicates the research hypotheses, sampling procedure, sample size, research design, testing conditions, stimuli, measures, data coding and aggregation method, criteria for data exclusions, and statistical analyses, including potential variations on those analyses. this preregistration document is then posted on a publicly available website such as the open science framework or aspredicted. the preregistered study is then conducted, and a report of the study and its results is submitted for publication together with access to the (anonymised) preregistration document. this preregistration approach allows peer reviewers and subsequent readers to cross-reference the preregistration document with the published research article in order to identify (a) any “exploratory” tests that were not included in the preregistration document and (b) any suppressed tests that were included in the preregistered protocol but excluded from the final research report. registered reports the registered report format requires authors to submit a description of the study methods and analyses prior to data collection. once the method and analysis plan is vetted through stage 1 peer review, publication of the findings is provisionally guaranteed. the associated study is then conducted, and the research report is submitted to stage 2 peer review. stage 2 peer review confirms that the actual research methods are consistent with the preregistered protocol and that quality thresholds are met (e.g., manipulation checks confirm the validity of the experimental manipulation). studies that pass stage 2 peer review are then published regardless of whether the results are confirming or disconfirming, significant or nonsignificant. hence, both preregistration and registered reports involve creating a time-stamped non-modifiable public record of the study and analysis plan before the data is collected. however, the study and analysis plan is only subjected to a formal peer review before data collection in the case of registered reports. specialised preregistration preregistration can be used in relation to a variety of different research designs and methods, including: quantitative research in psychology (bosnjak et al., 2021) qualitative research (haven & van grootel, 2019) preexisting data (mertens & krypotosm, 2019; weston et al., 2019; van den akker et al., 2021) single case designs (johnson & cook, 2019) electroencephalogram research (paul et al., 2021) experience sampling (kirtley et al., 2019) exploratory research (dirnagl, 2020) animal research (bert et al., 2019) clinical trial registration clinical trial registration is the practice of documenting clinical trials before they are performed in a clinical trials registry so as to combat publication bias and selective reporting. registration of clinical trials is required in some countries and is increasingly being standardized. some top medical journals will only publish the results of trials that have been pre-registered. a clinical trials registry is a platform which catalogs registered clinical trials. clinicaltrials.gov, run by the united states national library of medicine (nlm) was the first online registry for clinical trials, and remains the largest and most widely used. in addition to combating bias, clinical trial registries serve to increase transparency and access to clinical trials for the public. clinical trials registries are often searchable (e.g. by disease/indication, drug, location, etc.). trials are registered by the pharmaceutical, biotech or medical device company (sponsor) or by the hospital or foundation which is sponsoring the study, or by another organization, such as a contract research organization (cro) which is running the study. there has been a push from governments and international organizations, especially since 2005, to make clinical trial information more widely available and to standardize registries and processes of registering. the world health organization is working toward "achieving consensus on both the minimal and the optimal operating standards for trial registration". creation and development for many years, scientists and others have worried about reporting biases such that negative or null results from initiated clinical trials may be less likely to be published than positive results, thus skewing the literature and our understanding of how well interventions work. this worry has been international and written about for over 50 years. one of the proposals to address this potential bias was a comprehensive register of initiated clinical trials that would inform the public which trials had been started. ethical issues were those that seemed to interest the public most, as trialists (including those with potential commercial gain) benefited from those who enrolled in trials, but were not required to “give back,” telling the public what they had learned. those who were particularly concerned by the double standard were systematic reviewers, those who summarize what is known from clinical trials. if the literature is skewed, then the results of a systematic review are also likely to be skewed, possibly favoring the test intervention when in fact the accumulated data do not show this, if all data were made public. clinicaltrials.gov was originally developed largely as a result of breast cancer consumer lobbying, which led to authorizing language in the fda modernization act of 1997 (food and drug administration modernization act of 1997. pub l no. 105-115, §113 stat 2296), but the law provided neither funding nor a mechanism of enforcement. in addition, the law required that clinicaltrials.gov only include trials of serious and life-threatening diseases. then, two events occurred in 2004 that increased public awareness of the problems of reporting bias. first, the then-new york state attorney general eliot spitzer sued glaxosmithkline (gsk) because they had failed to reveal results from trials showing that certain antidepressants might be harmful. shortly thereafter, the international committee of medical journal editors (icmje) announced that their journals would not publish reports of trials unless they had been registered. the icmje action was probably the most important motivator for trial registration, as investigators wanted to reserve the possibility that they could publish their results in prestigious journals, should they want to. in 2007, the food and drug administration amendments act of 2007 (fdaaa) clarified the requirements for registration and also set penalties for non-compliance (public law 110-85. the food and drug administration amendments act of 2007 . international participation the international committee of medical journal editors (icmje) decided that from july 1, 2005 no trials will be considered for publication unless they are included on a clinical trials registry. the world health organization has begun the push for clinical trial registration with the initiation of the international clinical trials registry platform. there has also been action from the pharmaceutical industry, which released plans to make clinical trial data more transparent and publicly available. released in october 2008, the revised declaration of helsinki, states that "every clinical trial must be registered in a publicly accessible database before recruitment of the first subject." the world health organization maintains an international registry portal at http://apps.who.int/trialsearch/. who states that the international registry's mission is "to ensure that a complete view of research is accessible to all those involved in health care decision making. this will improve research transparency and will ultimately strengthen the validity and value of the scientific evidence base." since 2007, the international committee of medical journal editors icmje accepts all primary registries in the who network in addition to clinicaltrials.gov. clinical trial registration in other registries excluding clinicaltrials.gov has increased irrespective of study designs since 2014. reporting compliance various studies have measured the extent to which various trials are in compliance with the reporting standards of their registry. overview of clinical trial registries