Preregistration and registered reports are similar models, and both create a time-stamped, non-modifiable, public record of a study and analysis plan before data collection and analysis.
An important distinction between these forms and the more widespread concept of clinical trial registration is that the latter may not require the registration of a study's analysis protocol, the initially registered study design is not generally peer reviewed, and publication of the results is not dependent on the study being carried out as initially described.
With preregistered research articles there is a single published output, but it is peer-reviewed in two stages.
Stage 1: Researchers submit a protocol including the hypothesis, methodology and materials. The protocol is reviewed and accepted in-principle on the condition that the study is executed as approved.
Stage 2: Researchers complete the study and add the results and discussion to their approved Stage 1 protocol to create a single, integrated Preregistered Research Article. ("Preregistration" by PLOS is licensed under CC BY 4.0)
Some journals offer registries for accepted registered protocols. In other cases you can register it with an open registry. ("Future-proof your research. Preregister your next study." by Center for Open Science is licensed under CC BY 4.0)
With registered reports there are two linked peer-reviewed publications: the protocol and the study findings.
1. Registered report protocol. This describes the study rationale, methodology and any approvals needed. It is peer reviewed and given an in-principle acceptance (IPA). This guarantees publication of the final report regardless of findings, as long as the methodology is carried out as described or modifications made explicit. .
2. Registered report. The authors complete the study then submit a Registered Report, that is a full research article describing the study and its findings. ("Preregistration" by PLOS is licensed under CC BY 4.0)
Impartiality - Preregistration or registered reporting reduces tendencies to confirmation bias (selective reporting that confirms a hypothesis), hindsight bias (distorted interpretation of findings based on subsequent beliefs) and publication bias (selected publication of findings or omission of null findings).
Quality - Preregistration and registered reporting both emphasise the importance of the research questions and the strength of the proposed methods. They improve scientific rigour by ensuring clearer distinctions between confirmatory outcomes, which showcase results that reach a high standard of reproducibility, and exploratory outcomes, where data-led discovery generates new hypotheses.
Reproducibility - The replication crisis describes the phenomenon that many scientific studies are not replicable, their conclusions cannot be validated by further research, or the validity of the study methods cannot be scrutinised. Reasons include low statistical power, inadequate reporting of study methods, and unethical or sloppy data collection, analysis or reporting.
Transparency - Study designs are robustly documented and are available for others to judge the value and relevance of your final report, or to replicate or build on your research. Preregistration and registered reporting may reduce replication of effort and help researchers to find collaborators and understand research directions in their field.