Category Archives: Research Methodology

How to write a ‘Review of Literature’

Disclaimer: This article is primarily intended for my students participating in the Problem-Based Learning (PBL) program, but may benefit others as well.

Background Information:

The ‘Review of Literature’ section is critical to any research document. A well done review of literature

  • informs the materials and methods used;
  • assists with sample size calculation;
  • enables identification of gaps in knowledge; and
  • permits appropriate discussion of the results.

Key Messages:

General purpose

The review of literature must

  1. Provide clarity on technical terms used

    a. Generally, the first section should define important terms used later in the document. There are multiple definitions for most terms, and one cannot assume the reader is familiar with the perspective you are subscribing to. In the event that you describe multiple perspectives/ definitions, you must clearly state which of the many definitions has been adopted for the present investigation, and why. Defending/ explaining one’s choice(s) is crucial to establishing the validity of one’s approach. This should be done by citing appropriate literature, not by presenting one’s own opinion(s). From a technical standpoint, one’s opinion doesn’t count for anything- unless it has been published in a peer-reviewed article previously (in which case, the opinion would have been supported with literature; and the article in question should be cited appropriately).

    There are multiple definitions and concepts of health- from the World Health Organization (WHO) definition of health as a state of being, to the notion of health as mere absence of disease. The idea of health as the absence of disease may not be robust enough from a technical perspective, but may be important when discussing health from the perspective of the general public. Choosing one perspective over another depends upon the focus of the investigator, and should be justifiable when viewed in context of the investigation.

    b. Similarly, clearly stating the definition/ perspective adopted for a particular investigation allows others to verify if subsequent arguments are aligned with the initial position, or are in conflict.

  2. Describe what is already known

    One of the main purposes of a review of literature is to describe previous work done in the same area. This includes not just a broad description of the work done, but a detailed presentation of work that is relevant to the present investigation as well.

    This may include:
    description of various investigators’ work– including those pursuing approaches that conflict with your own. It is important to set personal prejudice aside and discuss the pros and cons of each approach, referring to supporting literature. You should be able to justify your decision to adopt a particular approach by critically analyzing the existing literature. This is particularly important if you are dealing with a controversial topic, or have adopted an unpopular/ unfamiliar approach. If so, you must provide enough information about the (unfamiliar) approach to enable the reader to comprehend subsequent arguments/ sections.

    discussion of tools available– these may be validated questionnaires, or other tools that have been developed over time. One is expected to have performed a comprehensive review of available tools before adopting a particular tool for use in the present investigation. Apart from a description of available tools, one must present reasonable justification for choosing a given tool over other alternatives. Often, such justification is on the basis of suitability for task; cost considerations; validity (of the lack of it); previous use in a similar population/ setting; license/ restrictions on use of tool, etc.

    Note: Failure to perform a thorough review of literature may result in the belated discovery that a better tool existed; or that one’s particular perspective has already been established/debunked. At that time, it may not be possible to revise the investigation.

  3. Indicate which aspects are less known/ controversial, and why

    A good review  of literature will expose the gaps in our knowledge, and lay the foundation for further investigations. However, one must provide some explanation regarding why particular areas have not been investigated; our knowledge in some areas is limited, etc. This requires a description of the difficulties/ challenges in investigation/comprehension. Inevitably, the complexity of the topic will come to the fore, and provide ample material for the discussion section later.

Writing style

a. The review of literature should be structured, with clear headings, sub-headings and sub-headings.


  1. Malnutrition
    1. Definitions
    2. Types
    3. Risk factors for development of malnutrition
    4. Pathophysiology
    5. Clinical Features
    6. Complications
    7. Assessment of malnutrition
    8. Management
      1. Severe Acute Malnutrition
        1. Community
        2. Hospital
      2. Chronic Malnutrition
    9. Prevention
      1. Interventions at the individual level
      2. Interventions at the family level
      3. Interventions at the community level

b. Instead of describing each research article, one should present statements/ arguments based on the articles.

Examples of good and bad practice:

What not to do:

  1. In a study done by ABC et al in Afghanistan, 3000 pregnant women ……..
  2. In another study done by BCA et al, 6524 pregnant women ……..

What to do:

Several investigators have reported the harmful effects of radiation during pregnancy.(1-6, 9)

c. Exercise restraint in your writing

Even if you have strong opinions about something/ someone, tone down your language. Excessively harsh criticism or exaggerated praise are not appreciated in scientific writing. The writing should be balanced in tone.

d. Substantiate all claims/ arguments with references to literature.

Avoid making unsubstantiated claims- they will merely dilute your argument and position.

e. Discuss topics and sub-topics in a logical manner

The sequence of topics, headings and sub-headings should follow a logical process.

f. Discuss one point per paragraph

This is to focus the attention of the reader on a single point at a time. However, each point should evolve from/ continue the narrative from the preceding paragraphs and sections.

g. Be consistent in your writing

Do not contradict yourself/ your stand. Take care to ensure that you are consistent throughout your document.

Determine which voice (active/ passive), and tense you will use in advance, then adhere to that rule.

h. Take a critical stand

Instead of simply describing what others say/ have done, examine their works critically, and voice your own position (while referring to literature).

i. Paraphrase

Don’t extensively quote others verbatim. It is good practice to paraphrase others’ work. Take care not to alter/ distort the meaning while paraphrasing. If you lack adequate skills to paraphrase, please seek the assistance of someone who can help.

Useful Link:

Link to article on sample size calculation using Epi Info (Cross-sectional studies):