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How can I preregister a study?

In a preregistration, you record your intentions regarding data collection and analysis. This clearly documents which ideas were specified in advance. When you choose to preregister, your choices come down to the format of the preregistration (especially the amount of detail and whether you use a pre-defined template) and the place where it is archived.

Format

In principle, the format of your preregistration is arbitrary as long as it states your plans clearly. Similarly, it need not be long, but any additional detail will help you prove that you followed a confirmatory research strategy. In practice, templates with pre-specified questions and prompts (as opposed to an open-ended, narrative preregistration) can help guide you through the process and make sure all critical questions are addressed.

The Open Science Framework has collected pre-made documents for each of these templates.

• AsPredicted boils the preregistration down to eight questions, and is probably the shortest and most straight-forward format available.
• Brandt et al. (2013) provide a recipe specifically for preregistering replications
• van 't Veer and Gina-Sorolla (2016) suggest a template geared toward experimental research, and helpfully distinguish between essential and optional, but recommended, elements.
• The OSF Prereg provides arguably the most comprehensive template.
• For (re)analyses of existing data, there's a secondary data preregistration template by Sara J. Weston and Marjan Bakker

Archive

As with the format, where you put your preregistration is up to you. A piece of paper in your desk drawer on which you sketched your hypotheses can be helpful, however, your preregistration becomes more convincing if a third party can vouch for the specific date on which you fixed your pre-registration (Corker, 2017, discusses different degrees of public commitment).

If you are using a service that archives files and records changes such as FigShare or Zenodo, you can pre-register by uploading your document to a public or private repository. Some services additionally simplify the process by providing a form and generating a record from your responses:

• AsPredicted provides an online version of its preregistration form, and generates an anonymous PDF file from the responses, which is accessible only using a secret link provided to the registrant. The link is never made public, so it is up to the authors to share it with reviewers and include it in manuscripts.
• The Open Science Framework allows for every project to contain registrations, which contain a snapshot of all files in the project as well any of the above templates, each of which the OSF provides in form of an online questionnaire. Registrations can be public directly, or embargoed to a maximum of four years. The OSF has provided a step-by-step written guide to preregistration as well as an extensive video tutorial.
• Further domain-specific archives also exist for a variety of subjects, such as ClinicalTrials.gov, run by the US National Library of Medicine, and other international clinical trials registry platforms as listed by the WHO, the registry for randomized controlled trials of the American Economic Association, Evidence in Governance and Politics or the Registry for International Development Impact Evaluations.