Best Practices in Research Reporting

Research submitted to PLOS must comply with internationally-accepted standards for research practice and reporting.

We reserve the right to enforce standards that may be more strict than local legal or ethical frameworks. Issues discovered after publication will be addressed according to guidelines of the Committee on Publication Ethics (COPE) and may lead to a correction, retraction, or expression of concern. We may also contact authors’ institutions as appropriate.

Ethical Oversight

We uphold rigorous standards for research ethics and expect authors to report on any ethical approvals required for their study. Read our policies on human subjects research and animal research. 

Inclusivity in Global Research

Authors of relevant research articles may be asked to complete an additional questionnaire outlining ethical, cultural, and scientific considerations specific to inclusivity in global research. The questionnaire may be requested when researchers have travelled to a different country to conduct research, the research uses samples collected in another country, the research was conducted with Indigenous populations or their lands, or the research was conducted on cultural artefacts. Researchers travelling to another country solely to use laboratory equipment will not normally be required to complete the questionnaire. However, the questionnaire can be requested for any submission.

This policy on inclusivity in global research aims to improve transparency in the reporting of research performed outside of researchers' own country or community and ensures that PLOS publications reporting global research adhere to high standards for research ethics and authorship. If requested by the journal, upload the completed questionnaire as a Supporting Information file so that it can be published with the manuscript. Authors performing research in other countries and communities should ensure the contribution of local collaborators is suitably acknowledged in the authorship list and/or Acknowledgements.

A copy of PLOS’ questionnaire on inclusivity in global research can be found here.

Reporting Research Protocols

Study design protocols, which describe the objective, rationale, and design of a specific study, may be uploaded as supporting information. Consult the supporting information guidelines for formatting details. If the protocol has been registered or published elsewhere, provide the accession number or DOI.

Authors are encouraged to share step-by-step protocols, which provide detailed and reusable instructions for carrying out the procedures used to generate their results, by depositing them at protocols.io and adding the DOI to their manuscript. Follow the instructions here for details: https://www.protocols.io/help/publish-articles. If methodological details beyond what is provided in the manuscript’s Materials and Methods section are available elsewhere, provide the DOI or other citation.

Reporting Guidelines for Specific Research Resources and Study Types

Authors are expected to comply with reporting guidelines for specific research resources and study types. The table below indicates selected guidelines and standards that are relevant to many PLOS authors; check the EQUATOR Network and the FAIRsharing Portal for specialized guidelines that may be relevant to your study design. Checklists or other documentation should be uploaded as supporting information at submission. Consult the submission guidelines for additional requirements. 

Statistical Reporting

Manuscripts are expected to report statistical methods, if used, in sufficient detail for others to replicate the analysis performed. Authors should ensure that results are rigorously reported in accordance with community standards and that statistical methods employed are appropriate for the study design.

In the Materials and Methods section, authors should include a section on statistical analysis that provides a detailed description of the statistical methods:

• List the name and version of any software package used, alongside any relevant references
• Describe technical details or procedures required to reproduce the analysis
• Provide a persistent identifier for any code used in the analysis (see our Code Sharing policy)

More specifically, authors should:

• Identify research design and independent variables as being between- or within-subjects
• For pre-processed data:
  • Justify the selection of statistical tests by describing any analysis confirming that the data meets the assumptions of the analysis performed (e.g., linearity, collinearity, normality of the distribution)
  • If data were transformed, provide a reason for doing so and a description of the transformation performed
• Provide details of how outliers were treated and analysis, both with the full dataset and with the outliers removed
• If relevant, describe how missing/excluded data were handled, including attrition effects. Provide details of any blinding, methods of randomization, or inclusion/exclusion criteria (e.g., of subjects included at collection or of data points included in analysis)
• Define the threshold for significance (alpha)
• If appropriate, provide sample sizes, along with a description of how they were determined. If a sample size calculation was performed, specify the inputs for power, effect size and alpha. Where relevant, report the number of independent replications for each experiment and whether replicates were derived from different experimental units/subjects or from multiple contemporary measurements of the same experimental unit/subject
• For analyses of variance (ANOVAs), detail any post hoc tests that were performed
• Include details of any corrections applied to account for multiple comparisons. If corrections were not applied, include a justification for not doing so
• Describe all options for statistical procedures. For example, if t-tests were performed, state whether these were one- or two-tailed. Include details of the type of t-test conducted (e.g. one sample, within-/between-subjects)
• For stepwise multiple regression analyses:
  • Report the alpha level used
  • Discuss whether the variables were assessed for collinearity and interaction
  • Describe the variable selection process by which the final model was developed (e.g., forward-stepwise; best subset)
• For Bayesian analysis explain the choice of prior trial probabilities and how they were selected. Markov chain Monte Carlo settings should be reported.

Results must be rigorously and appropriately reported, in keeping with community standards.

• Units of measurement. Clearly define measurement units in all tables and figures.
• Properties of distribution. It should be clear from the text which measures of variance (standard deviation, standard error of the mean, confidence intervals) and central tendency (mean, median) are being presented.
• Regression analyses. Include the full results of any regression analysis performed as a Supporting Information file. Include all estimated regression coefficients, their standard error, p-values, and confidence intervals, as well as measures of goodness of fit.
• Reporting parameters. Test statistics (F/t/r) and associated degrees of freedom should be provided. Effect sizes and confidence intervals should be reported where appropriate. If percentages are provided, the numerator and denominator should also be given.
• P-values. Report exact p-values for all values greater than or equal to 0.001. P-values less than 0.001 may be expressed as p < 0.001, or as exponentials in studies of genetic associations.
• Displaying data in plots. Format plots so that they accurately depict the sample distribution. 3D effects in plots can bias and hinder interpretation of values, so avoid them in cases where regular plots are sufficient to display the data.
• Open data. As explained in PLOS’s Data Availability policy, be sure to make individual data points, underlying graphs and summary statistics available at the time of publication. PLOS strongly recommends depositing data in a repository, but it may also be included as supporting information.

Authors may also consult the SAMPL guidelines for additional guidance.

Territorial Descriptions

Territorial descriptions in submitted manuscripts should follow international treaties and conventions. PLOS remains neutral on any jurisdictional claims expressed or implied in published manuscript texts, maps and institutional affiliations.