How to Read a Manuscript as a Peer Reviewer

Man taking notes next to a laptop

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What should you focus on when you review a scientific manuscript? This guide walks you through the process of reading a paper and identifying key things to mention in your review.

Important Reminders

You have two main jobs as a reviewer:

  1. Determine whether the authors’ claims are supported
  2. Help the journal editors make their decision

Journal editors make their decisions based on the journal’s publication criteria, read these before you start your review. Remember that the editors may not be experts in the field. They need you because of your specialized knowledge and technical expertise. They do not need you to be a copy editor.

Getting Started

The first step when reading is to figure out what the authors are trying to claim. It might be helpful to ask yourself these questions:

  • What is the study about? What is the main research question?
  • What is the approach? What did the authors do to address their research question?
  • What is the context? How does the study relate to published literature on this topic?
  • What are the conclusions? What are the authors’ main findings and what evidence do they provide for these conclusions?

Make sure you read the entire manuscript, including the figures. You should expect to read through the manuscript at least twice. It’s generally a good idea to read start to finish, but this is not always the case.

Here’s one way to read the manuscript that involves going a bit out of order:

  1. Read the abstract and introduction to get a sense of the overall context and approach (if the abstract and introduction do not do a good job summarizing the findings, you might need to read further to get this information).
  2. Look at the figures and tables carefully in conjunction with the results.
  3. Read the conclusions.
  4. Then read the whole thing from beginning to end.

Take lots of notes as you go along to get a jump start on writing your report.

Paper or pixels: What's your reading style?

Do you prefer reading on screen or holding a hard copy? Whether you prefer to mark up an online PDF, or take notes with a pen or pencil, it’s up to you to come up with a reviewing method that works for you.

Recent surveys of PLOS reviewers indicate that 43% prefer to read manuscripts in hard copy. Want to help us gather more data about peer review? Tell us how you like to read:

Poll: When I am reviewing a manuscript, I prefer to read it:

Tips for Specific Sections

Here’s a section-by-section guide of things to look for. You might want to take notes about what each section includes and identify the strengths and weaknesses.

Abstract and introduction

The introduction sets the stage. The authors should explain why the study matters and put the research in context.

  • Do the authors summarize the main research question and key findings?
  • Do the authors identify other literature on the topic and explain how the study relates to this previously published research?

Figures and tables

Make sure the manuscript text supports the data shown in the figures and tables. Do not just take the figures and tables at face value.

  • Are the figures and tables clear and readable? (Keep in mind that depending on the submission system you’re working in, you might have to click a link to view the high-resolution versions of the authors’ figures).
  • Are the figure and table captions complete and accurate?
  • Are the axes labeled correctly?
  • Is the presentation appropriate for the type of data being presented?
  • Do the figures and tables support the findings?

Methods

When you assess the methods used in the study, you are looking to determine whether the research is technically sound. Some questions you might consider, depending on the type of study, include:

  • What experiments or interventions were used?
  • Are the experiments or interventions appropriate for addressing the research question?
  • Are conditions adequate and the right controls in place?
  • Is there enough data to draw a conclusion?
  • Do the authors address any possible limitations of the research?
  • Was data collected and interpreted accurately?
  • Do the authors follow best practices for reporting?
  • Does the study conform to ethical guidelines?
  • Could another researcher reproduce the study with the same methods? In other words, have the authors provided enough information to validate the study?

Results, discussion, conclusions

  • Do the results support the conclusions?
  • Do the conclusions overreach?
  • Do the authors discuss any limitations of the study?
  • If the journal selects based on advance in the field does the study demonstrate this advance?

Statistical analysis

Is the statistical analysis adequate? If you do not have the expertise to consider the statistics, make sure you mention this in your report.

Data and supporting information

  • Do the data provide enough evidence for the authors’ conclusions?
  • Are the necessary data points provided?
  • Have the authors provided a sufficient amount of data and information for other researchers to recreate the analyses?

Reminder: Keep it confidential!

Reviewing manuscripts is a great way to stay on top of the latest research in your field. Just remember that everything you have access to as a reviewer needs to stay confidential until the work is published. We know it can be exciting to read about a new discovery or development, but avoid the temptation to talk to other people about the research, and never use the information for your own personal gain.

For more helpful tips about best practices in the review process, check out our ethics guide for reviewers.

Other Things to Check

Here are some additional things to look at when you’re reading.

Writing quality & clarity

As a reviewer, you should focus on the substance of the research rather than the writing. If you think the quality of the writing needs to be improved, don’t spend your time pointing out individual typos and other minor details. Just mention in your comments that you recommend language editing.

Plagiarism

If you have reason to believe the authors might have plagiarized, contact the journal immediately. If there is a confidential comments to the editor section of the reviewer report add your concerns there.

Reference list

Check the references in the manuscript. Mention any literature that is missing from the list, but don’t use this as an opportunity to request citations for your own work.

Wrapping Up

After you have carefully read the manuscript and taken notes on overall strengths and weaknesses, take another look at the journal’s publication criteria and reviewer guidelines. Determine if you need to look at any part of the manuscript again. Go over your notes and decide what you’ll recommend to the journal.

Tip: How much time should you spend on the review?

It can take time to complete a good review, and some types of studies might take you longer than others. Be prepared for reviewing to take longer when you’re just starting out. As you gain more experience, you’ll probably start to work more quickly. Everyone reviews differently so there’s no specific benchmark to strive for.

In general, it’s a good idea to spread your work out over a couple of days (or at least a couple of sessions). Sleep on it! Give your thoughts time to develop.

If you’re not sure how much time to spend on the review, or if you’re having trouble managing the amount of time you’re spending, try setting a timer for yourself or blocking out a specific time of day to get the work done.

You’ve read the manuscript and taken lots of notes. Now you’re ready to write your report! Read our next guide about how to write a review.