The University of Arizona

NIH Peer Review Process

On this page:

The NIH Peer Review Process
Overview of Peer Review
Peer Review Resources
Review Criteria
Rigor & Reproducibility
Serving as a Reviewer

The NIH Peer Review Process

The National Institutes of Health (NIH) Office of Extramural Research (OER) provides a Grants Process Overview detailing the steps required to proceed from application planning and submission through award and close out. 

The process takes between nine and ten months and is comprised of the following steps:

  1. Peer Review
  2. Advisory Council Review
  3. Funding Decision

Once submitted to NIH, your application is checked for completeness. Errors related to application processing are flagged by Grants.gov and errors related to the application requirements are detected by the eRA system. Any errors identified at this stage must be addressed and the application resubmitted. Thus, it is important to submit early so that errors can be corrected prior to the submission deadline! Once the application is error-free, it is placed in a queue for retrieval by NIH. Applications are then manually checked by NIH staff for fit with the NIH mission, overlap with other applications you may have under review, and compliance with the FOA instructions and NIH formatting requirements. Failure to comply with all NIH guidelines could result in the withdrawal/rejection of your application by NIH.

Overview of Peer Review

The Center for Scientific review (CSR) receives and conducts the peer review of the majority of proposals submitted to NIH (approximately 75%). The  Division of Receipt and Referral (DRR) within CSR handles the receipt of grant applications and the assignment of applications to a Scientific Review Group (SRG) or study section, a group of primarily non-federal scientists with expertise in areas relevant to the NIH mission and the specific NIH Institutes and Centers (ICs). It is important to identify a study section that is appropriate for the review of your proposal, as applicants can indicate their preferred study section and funding institute as part of their application using the PHS Assignment Request Form (ARF), as described in the SF424 Application Guide.

NIH utilizes a two-level peer review process:

  • The first level of review is managed by either CSR or one of the NIH Institutes and Centers (IC) and is carried out by a study section. The majority of investigator-initiated applications (R01, R03, R21, and K awards) are reviewed by Standing Study Sections, whereas some applications, if specified in the FOA, are reviewed by Special Emphasis Panels.
    • Scoring: The NIH grant application scoring system uses a 9-point rating scale (1 = exceptional; 9 = poor) in whole numbers (no decimals) for Overall Impact and Criterion (Significance, Investigators, Innovation, Approach, Environment) scores for all applications, with a score of 5 considered an average score. Reviewers assigned to a given application submit preliminary scores (overall and criterion) prior to the study section meeting, which are often used to determine the proposals that are discussed at the meeting. After discussion, final impact and criterion scores are submitted by the assigned reviewers and eligible study section members. The final overall impact score is calculated by multiplying the mean of the final impact scores by 10 and reported on the summary statement.
    • Percentiles: A percentile is the approximate percentage of applications that received a better overall impact score from a given study section over the past year
  • The second level of review is carried out by each NIH IC Advisory Council/Board, which are composed of both scientific and public representatives selected for their expertise relevant to the given NIH IC. The Advisory Board/Council considers the research priorities of the given IC and input from the relevant program staff as well as the overall impact scores awarded during the first level of peer review, the percentile scores (if applicable), and the summary statements before making funding recommendations.

Only applications that are endorsed by the study section, program staff, and the Advisory Council are recommended for funding.  Final funding decisions are made by the Directors of the respective NIH ICs.

Peer Review Resources

CSR provides a number of resources for experienced and early career investigators

  • Applicant Resources – videos on peer review, the Early Career Reviewer Program (see Serving as a Reviewer), tips for applicants, and navigating NIH peer review
  • Assisted Referral Tool – an online tool that matches the title/abstract/aims of your application to appropriate CSR study sections
  • Study Section Roster Index – lists all current study section participants of standing, fellowship, SBIR/STTR, and other CSR study sections
  • Integrated Review Groups – lists CSR Integrated Review Groups (IRGs), which are clusters of study sections in a general scientific area

OER provides information on peer review compliance and oversight for both investigators and reviewers

  • NIH Grants Policy Statement – information on the terms and conditions of NIH grant awards and a link to the consolidated NIH policy requirements document as well as notices of recent policy changes. 
  • Peer Review Policies and Practices - information on peer review regulations and policies, including conflict of interest, rigor & reproducibility, human subjects and vertebrate animals, and scoring procedures for research applications.
  • Information for Reviewers – resources on the peer review process and related policies including updates to peer review criteria, pre-meeting logistics, and preparing for review, including guidance on scoring and writing critiques.
  • Rigor and Reproducibility - guidance on Rigor and Reproducibility in grant applications, including detailed descriptions of each component and links to other helpful resources.

Review Criteria

NIH review criteria are specific to the type of funding mechanism (e.g., research project grant [R-series, U-series], career award [K awards], training grant [T-series], etc.). The NIH OER website provides a full description of the review criteria, downloadable guidelines for reviewers, and fillable review critique templates for all NIH funding mechanisms. The scored review criteria for research project grants include: 1) Significance, 2) Investigator(s), 3) Innovation, 4) Approach, and 5) Environment. In addition, reviewers also provide an Overall Impact score that reflects their evaluation of the potential for the project to impact the relevant research field, as determined by their assessments of the scored review criteria.

More information, including additional guidance, additional (unscored) review criteria, and additional considerations, can be found on the NIH OER website for all NIH funding mechanisms (link leads to review criteria and more information for research project grants).

Rigor & Reproducibility

To promote rigorous and transparent research, the NIH updated grant application instructions and review language to enhance reproducibility through rigor and transparency. These changes have been implemented for research grants and mentored career development awards. Updates to institutional training grants, institutional career development awards, and individual fellowships are forthcoming. The updated application instructions and review language focus on four key areas:

Scientific Premise

Description: The scientific premise for an application is the research that is used to form the basis for the proposed research question(s). NIH expects applicants to describe the general strengths and weaknesses of the prior research being cited by the applicant as crucial to support the application. It is expected that this consideration of general strengths and weaknesses include attention to the rigor of the previous experimental designs, as well as the incorporation of relevant biological variables and authentication of key resources.

Review Criteria: Reviewers evaluate scientific premise as part of the Significance criterion for research grant applications and assess whether the applicant has discussed the strengths and weaknesses of the foundational data and described how the proposed research will address the identified weaknesses or gaps.

Scientific Rigor

Description: Scientific rigor is the strict application of the scientific method to ensure robust and unbiased experimental design, methodology, analysis, interpretation, and reporting of results. This includes full transparency in reporting experimental details so that others may reproduce and extend the findings. Note: Scientific premise pertains to the strengths/weaknesses of the supporting data, whereas scientific rigor pertains to the proposed research.

Review Criteria: Reviewers assess scientific rigor as part of the Approach criterion and the overall impact score. The reviewers will evaluate the experimental design, including descriptions of experimental controls, plans to reduce bias (blinding, randomization, subject inclusions and exclusion criteria, etc.), power analyses, and statistical methods.

Consideration of Relevant biological variables

Description: Biological variables, such as sex, age, weight, and underlying health conditions, are often critical factors affecting health or disease. In particular, sex is a biological variable that is frequently ignored in animal study designs and analyses, leading to an incomplete understanding of potential sex-based differences in basic biological function, disease processes and treatment response.

Review Criteria: Reviewers assess the applicant's plans to address relevant biological variables, such as sex, as part of the Approach criterion score and the overall impact score. If the applicant proposes the use of only one sex, reviewers will assess the justification provided by the applicant.

Authentication of key biological and/or chemical resources

Description: Key biological and/or chemical resources include, but are not limited to, cell lines, special chemicals, antibodies, transgenic animals, and other biologics. Key biological and/or chemical resources may or may not be generated with NIH funds and i) may differ from laboratory to laboratory or over time; ii) may have qualities and/or qualifications that could influence the research data; and iii) are integral to the proposed research.

Review Criteria: Reviewers discuss the adequacy of the plan for key resource authentication after scoring; thus, comments on key resource authentication should not affect scores. Nonetheless, if the authentication plan is inadequate or missing from the application, it will be reflected in the written critiques.

For more detailed guidance and resources on Rigor & Reproducibility, please see the RDS Preparing a Proposal to the National Institutes of Health page.

Serving as a Reviewer

In addition to providing a number of resources for applicants, including information on the peer review process and the different study sections, CSR provides important resources for reviewers, including how to become a NIH reviewer. As an incentive, the NIH allows reviewers to submit their research grant applications (R01, R21, or R34) on a continuous basis for serving as a reviewer.

NIH specifically seeks the participation of early career reviewers through their Early Career Reviewer (ECR) program. To be considered for the ECR program, individuals must have 2 years of experience in a full-time faculty or research position, show evidence of an active independent program of research, have at least two recent senior-authored research publications, and may have not served on a CSR study section (mail reviews are not counted). Current funding is not required.