how to critically evaluate scientific research

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Critical evaluation of publications

N gopi chander.

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Address for correspondence: Dr. N. Gopi Chander, Professor, Department of Prosthodontics, SRM Dental College, SRM University, Chennai - 600 089, Tamil Nadu, India. E-mail: [email protected]

Received 2020 Nov 30; Accepted 2020 Dec 16; Issue date 2021 Jan-Mar.

This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.

Critical evaluation is the process of examining the research for the strength or weakness of the findings, validity, relevance, and usefulness of the research findings.[ 1 ] The availability of extensive information and the difficulty in differentiating the relevant information obligate the primary need of critical appraisal. In addition, it establishes superior evidence and increases the application to clinical practice.[ 2 ] More importantly, it differentiates between significant and/or insignificant data in the literature and aids in providing the updated information. The purpose of critical appraisal shall help in informed decision and improve the quality of healthcare provided to patients.[ 1 , 2 , 3 ]

The research data have three possible outcomes – true findings, random variation that occurs due to chance, and biased results due to systematic error.[ 4 ] The true findings can be of positive or negative results, but it shall be highly recognized. The random error or actual result deviation occurs due to the uncontrollable factors such as smaller sample size and confounding factors. The random error does not alter the measured value, but it is an imperfect error caused due to study design inconsistencies. These errors are unpredictable and cannot be repeated again by repeating the analysis. The biased results are deliberate deviation in the study design, methodology, or investigations. The deviations in the result can be due to poor designing, to the methodology, or in the analysis. It will be difficult to differentiate these findings without critical analysis of the literature.[ 5 , 6 ]

There are various guidelines and tools proposed to critically evaluate the literature.[ 7 , 8 , 9 ] Since the scientific literature is in constant evolution, no one guidelines or checklist is considered to be gold standard. Moreover, the appraisal varies with the type of research. The checklist provided by various organizations for designing or structuring manuscripts - case report, reviews, and original research - cannot be combined or generalized for use. Similarly, it varies with the types of study design - randomized clinical trials and observational studies –case–control, cohort, and cross-sectional studies. The methodological guidelines such as consort statements, CARE guidelines, PROSPERO, or Cochrane checklists can significantly aid in the evaluation of different types of research data.[ 10 ] The structured approach and checklists provided by the organizations can be a valuable aid to conduct research as well as critically evaluate the manuscripts. In addition to the guidelines, the simplified checklists proposed by Young and Solomon can be of adjuvant tool in critical assessment of the literature.[ 1 ] It consists of 10 simple rules. That includes relevance of study question, new information to existing literature, type of research question, appropriateness of study design, bias appraisal, adherence of study protocol, hypothesis testing, check or estimation of statistical analysis, validation of conclusion, and identification of conflicts of interest. These checklists along with updated methodological guidelines for different types of study designs can be a valuable tool for critical appraisal of the literature.[ 1 , 10 ]

Most of the tools assess the validity, reliability, bias, and clinical application of the research data. The validity aids in determining the accuracy of the results, and the reliability establishes the consistency of the results. The bias is systemic deviation of results. The bias is of many types: it can be of from the initiation of the study to manuscript publication. Various assessment tools have been proposed to determine the bias. More commonly employed are the GRADE, Grade pro, Newcastle Ottawa, jaded, ROB 2, and ARRIVE 2.[ 11 ] The bias tools vary with the type of study design, and it is significant to use the appropriate tool. The tools assess and grade the quality of bias in the manuscript. These tools are majorly used for evaluating randomized control trial employed for systematic review and meta-analysis but can be suitably employed to different study designs. These tools provide the grading of bias and provide useful data that are essential for clinical application.[ 11 , 12 ]

Rapid appraisal can be done with merit trials/rapid critical appraisal tool.[ 6 ] It is a compressed tool that basically assesses on the validity, reliability, and clinical use of the study. This is a simplified checklist for quicker assessment; however, for more accurate assessment, it is essential to appraise the entire manuscript from introduction till the conclusion. This mandates a detailed check for every component of the literature in accordance to the standard guidelines. In addition, the journal indexing and metrics can play a significant role in estimation. Higher metric journal shall possess more rigorous peer-review process that reduces the significant errors in the manuscript.[ 3 , 4 ]

The major contents to be generally assessed in the introduction of the manuscript are type and contents of research question, justification of purpose/background of the study with articles published in the last 5 years, or older articles that possess significant influences, citations of peer-reviewed journal, defined objective, and hypothesis statement. In methodology, the parameter of appraisal parameters should be on study design, inclusion and exclusion criteria, care in reduction of bias, following the acceptable procedures, control on confounding variables, and valid outcome measures. The result section should be checked for the subject and baseline - demographic, relevant statistical tests, and statistical significance. The discussion should possess adequate literature substantiation for results, study limitations, and declarations on conflicts of interest.[ 6 ]

In the prosthodontic literature, extensive reports of similar nature exist; critical analysis of the literature is a necessary skill to be mastered by researchers and clinicians.[ 10 ] It helps clinicians to make quality evidenced healthcare decisions by extensive evaluation of the literature.

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How to read a paper, critical review

Reading a scientific article is a complex task. The worst way to approach this task is to treat it like the reading of a textbook—reading from title to literature cited, digesting every word along the way without any reflection or criticism.

A critical review (sometimes called a critique, critical commentary, critical appraisal, critical analysis) is a detailed commentary on and critical evaluation of a text. You might carry out a critical review as a stand-alone exercise, or as part of your research and preparation for writing a literature review. The following guidelines are designed to help you critically evaluate a research article.

How to Read a Scientific Article

You should begin by skimming the article to identify its structure and features. As you read, look for the author’s main points.

• Generate questions before, during, and after reading.
• Draw inferences based on your own experiences and knowledge.
• To really improve understanding and recall, take notes as you read.

What is meant by critical and evaluation?

• To be critical does not mean to criticise in an exclusively negative manner. To be critical of a text means you question the information and opinions in the text, in an attempt to evaluate or judge its worth overall.
• An evaluation is an assessment of the strengths and weaknesses of a text. This should relate to specific criteria, in the case of a research article. You have to understand the purpose of each section, and be aware of the type of information and evidence that are needed to make it convincing, before you can judge its overall value to the research article as a whole.

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• How to read a scientific paper
• How to conduct a critical review

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• Published: 11 November 2024

How to write an excellent Review article

Nature Reviews Bioengineering volume  2 ,  page 907 ( 2024 ) Cite this article

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Review articles are our bread and butter. Here, we would like to offer some insights on how to craft a comprehensive and authoritative assessment of a field.

Only by taking stock of where we are, can we point to where we need to go next. Review articles are designed to synthesize and critically evaluate the most important research findings within a specific field to gauge its progress and identify new research opportunities. They should be timely, objective, balanced, forward-thinking and engaging — not only informative but also easy to read. So, what does it take to craft a high-quality Review that serves as an essential resource for those interested in your field?

The first step is to determine whether your topic is timely and whether there is sufficient recent primary research to justify a crucial discussion. Start by thoroughly scanning the scientific literature to identify key findings, open questions, emerging insights, controversies and recent conclusions. A good rule of thumb is to aim for at least 30 relevant primary research papers published within the past 2–3 years. If you can meet this benchmark, it may be a good time to assess the field through a Review and start screening the broader literature. When identifying references, use a range of sources, such as literature databases and community-specific resources, and experiment with different keyword combinations to ensure comprehensive coverage. It is also beneficial to follow the work of a diverse set of researchers to get a sense of what is trending globally. Because references are the foundation of your article, make sure to cite appropriately and be mindful of inclusivity and diversity in your citations 1 .

Next, you need to find a compelling angle for your discussion. Ask yourself whether new research results have led to fresh questions or if certain areas are approaching clinical application. If not, are there emerging research directions aimed at bridging the translational gaps? Has the field shifted toward a new focus or approach? Identifying this angle will shape the narrative of your Review.

Begin by drafting a detailed outline. Identify the main topics, examples and key messages you want to convey. Organize these into a coherent storyline, drawing connections and highlighting synergies between different research areas. In addition, consider designing original illustrations that summarize the core concepts, compare different approaches and showcase key examples. Visual elements are powerful tools to enhance understanding and can help readers to grasp complex ideas quickly.

The introduction to your Review should set the stage by providing an overview of the field and context for the topic. Keep in mind that your audience may include readers who are unfamiliar with the subject, so explain mechanisms and concepts clearly and in sufficient detail. However, avoid overcomplicating things — simplicity is key. Steer clear of acronyms and abbreviations, as their meanings can vary across disciplines and may confuse readers, and keep sentences and paragraphs concise. Be sure to highlight the major advancements and knowledge gaps, emphasizing the importance and impact of the field you are reviewing.

The core of the Review — the critical discussion — should follow a logical flow. Organize the content into major sections, each dedicated to a particular area of research, with sub-sections to help to structure the discussion. Do not merely list research outcomes in chronological order; instead, compare and contrast the most representative research findings, exploring what has succeeded, what has not, and what can be learned from any failures. Look for common themes, conflicting conclusions and bottlenecks. Be as specific as possible, offering detailed information about models, systems and methodologies. To avoid ambiguity, make sure it is clear whether you are discussing established findings or proposing hypotheses. Incorporate tables to compare systems, metrics or approaches — such as clinical trials, performance outcomes or device designs — and consider adding text boxes for technical details that support the main discussion.

Conclude your Review with an outlook section that summarizes the key take-home messages and highlights future directions for the field, pinpointing specific actionable milestones. By the end, readers should have a clear understanding of the current state of the field, its future challenges, and the steps needed to overcome them from both engineering and translational perspectives. Ideally, the reader is left with many ideas for new experiments and collaborations.

Finally, choose a title that is clear, descriptive and concise, avoiding vague terms, such as ‘advances’, ‘emerging’ or ‘recent’, to make your Review easy to find and classify. The title should include key terms that reflect the content of the Review. Similarly, the abstract should be succinct, providing a snapshot of the article by briefly introducing the field and outlining the major themes of your article. Think of it as a miniature version of the Review.

“A good Review should always teach you something new — even if you have been in the field for a long time.”

A good Review should always teach you something new — even if you have been in the field for a long time. Writing a Review article offers a unique opportunity to reflect on a field and deepen your understanding of core concepts. The process might even lead you to fresh insights of your own.

Citation diversity statement. Nat. Rev. Bioeng. 1 , 227 (2023).

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How to write an excellent Review article. Nat Rev Bioeng 2 , 907 (2024). https://doi.org/10.1038/s44222-024-00256-4

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Published : 11 November 2024

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DOI : https://doi.org/10.1038/s44222-024-00256-4

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