19. Protocol registration Provide a statement indicating whether a protocol (including the research question, key design features, and analysis plan) was prepared before the study, and if and where this protocol was registered. explanation

Akin to the approach taken for clinical trials, protocol registration has emerged as a mechanism that is likely to improve the transparency of animal research [1-3]. Registering a protocol before the start of the experiment enables researchers to demonstrate that the hypothesis, approach and analysis were planned in advance and not shaped by data as they emerged; it enhances scientific rigour and protects the researcher against concerns about selective reporting of results [4,5]. A protocol should consist of a) the question being addressed and the key features of the research that is proposed, such as the hypothesis being tested and the primary outcome measure (if applicable), the statistical analysis plan; and b) the laboratory procedures to be used to perform the planned experiment.

Protocols may be registered with different levels of completeness. For example, in the Registered Report format offered by an increasing number of journals, protocols undergo peer review and if accepted, the journal commits to publishing the completed research regardless of the results obtained [1].

Other online resources include the Open Science Framework [6], which is suitable to deposit PHISPS (Population; Hypothesis; Intervention; Statistical analysis plan; Primary outcome measure; Sample size calculation) protocols [7] and provide researchers with the flexibility to embargo the preregistration and keep it from public view until the research is published, and selectively share it with reviewers and editors. The EDA can also be used to generate a time-stamped PDF, which sets out key elements of the experimental design [8]. This can be used to demonstrate that the study conduct, analysis and reporting were not unduly driven by emerging data. As a minimum we recommend registering protocols containing all PHISPS components as outlined above.

Provide a statement indicating whether or not any protocol was prepared before the study, and if applicable, provide the time-stamped protocol or the location of its registration. Where there have been deviations from the protocol, describe the rationale for these changes in the publication so that readers can take this into account when assessing the findings.

References

1. Chambers CD, Feredoes E, Muthukumaraswamy SD and Etchells PJ (2014). Instead of "playing the game" it is time to change the rules: Registered Reports at AIMS Neuroscience and beyond. AIMS Neuroscience. http://doi.org/10.3934/Neuroscience.2014.1.4
2. Chalmers I, Bracken MB, Djulbegovic B, Garattini S, Grant J, Gülmezoglu AM, Howells DW, Ioannidis JPA and Oliver S (2014). How to increase value and reduce waste when research priorities are set. The Lancet. doi: 10.1016/S0140-6736(13)62229-1
3. Nosek BA and Lakens D (2014). Registered Reports a method to increase the credibility of published results. Soc Psychol-Germany. doi: 10.1027/1864-9335/a000192
4. Kaplan RM and Irvin VL (2015). Likelihood of Null Effects of Large NHLBI Clinical Trials Has Increased over Time. Plos One. doi: 10.1371/journal.pone.0132382 
5. Allen C and Mehler D (2018). Open Science challenges, benefits and tips in early career and beyond. PsyArXiv. doi: 10.31234/osf.io/3czyt
6. Nosek BA, Ebersole CR, DeHaven AC and Mellor DT (2018). The preregistration revolution. Proceedings of the National Academy of Sciences of the United States of America. doi: 10.1073/pnas.1708274114
7. Macleod M and Howells D (2016). Protocols for laboratory research. Evidence-based Preclinical Medicine. doi: doi:10.1002/ebm2.21
8. Percie du Sert N, Bamsey I, Bate ST, Berdoy M, Clark RA, Cuthill I, Fry D, Karp NA, Macleod M, Moon L, Stanford SC and Lings B (2017). The Experimental Design Assistant. PLoS Biol. doi: 10.1371/journal.pbio.2003779