Literature Review

Mr. Arvind Kumar

Literature Review

  • A literature review is a critical synthesis of existing research and information relevant to a particular research topic or problem.
  • It serves as the foundation upon which new research is built, helping researchers identify gaps in existing knowledge, discover trends, and support their research design.
  • To create a comprehensive and reliable literature review, researchers need to access various sources of information.

 

Sources of Information

  • The sources of information for literature reviews are vast and varied.
  • Researchers can access both traditional and electronic resources, including print versions of books and journals, electronic databases, and web resources.
  • Below, we outline some of the most widely used sources and methods for gathering literature for your review.

Using the Library

  • Libraries are traditional but invaluable resources for research.
  • University libraries and public libraries often provide access to a wide range of materials, including physical copies of books, journals, and other reference works.
  • Academic libraries, in particular, are known for their extensive collections of scholarly resources, including rare or older materials not easily found online.

Points for Using the Library:

  • Catalogues and Archives: Libraries usually offer online catalogues that allow you to search for books, academic papers, and other printed materials. You can find comprehensive historical works or specialized books that may not be digitized.

  • Library Assistance: Librarians can guide you on how to conduct literature searches, how to access resources, and even help with identifying key sources on your topic.

  • Interlibrary Loan Systems: If your library doesn’t have a certain book or journal, it is often possible to request it through interlibrary loans from other libraries.

 

Bibliographical Databases

Bibliographical databases are essential tools for finding academic papers, journal articles, conference proceedings, and more. These databases allow researchers to search for sources using specific keywords, authors, titles, and subjects.

Common Bibliographical Databases:

  • PubMed: A major resource for health and biomedical research, providing access to millions of citations from medical literature.

  • Scopus: A comprehensive database that covers a wide range of subjects, including health, life sciences, social sciences, and more.

  • Web of Science: Provides access to a vast amount of multidisciplinary research, offering citation analysis tools to track trends in academic publications.

  • PsycINFO: A database specializing in psychology and related fields, perfect for researchers studying mental health and behavioral sciences.

Using bibliographical databases allows you to locate peer-reviewed articles, thesis papers, books, and other scholarly work. It is important to use relevant keywords and search filters to narrow down the results to the most pertinent studies.

Print Version

While the use of electronic resources is increasing, printed sources remain a valuable part of any literature review. Books, academic journals, and government reports often provide in-depth, comprehensive perspectives on a topic. These sources can be particularly valuable for obtaining foundational knowledge on the topic.

Examples of Printed Sources:

  • Academic Textbooks: These can provide foundational theories, historical context, and an overview of key issues.

  • Journals: Print versions of journals like The Lancet, Journal of Clinical Investigation, and others still remain relevant, especially in older studies or those not yet digitized.

  • Reports: Government and health administration reports often offer detailed statistics, policy recommendations, and frameworks for understanding public health and policy changes.

While print versions of academic works are still in use, it is recommended to supplement them with electronic sources for the most current and comprehensive data.

Electronic Versions of Journals and Books

The rise of digital technology has drastically expanded access to academic literature. Many journals and books are now available in electronic formats, allowing researchers to access materials from anywhere at any time. This includes online journal articles, eBooks, and digital repositories.

Advantages of Electronic Versions:

  • 24/7 Access: Researchers can access journals and books at their convenience.

  • Searchability: Electronic versions often allow for keyword searches, making it easier to locate specific sections or information.

  • Interactivity: Many electronic platforms provide features like bookmarking, highlighting, and sharing, making it easier to organize and manage research.

Popular platforms that provide access to electronic versions of journals and books include:

  • Elsevier’s ScienceDirect (for life sciences and health)

  • SpringerLink (for scientific and academic content)

  • Wiley Online Library (for books and journals across various disciplines)

 

NLM’s MEDLINE Databases

The National Library of Medicine (NLM), through its MEDLINE database, is one of the most widely used sources for health-related literature. MEDLINE provides access to millions of citations and abstracts from biomedical and life sciences literature.

Features of MEDLINE:

  • Peer-Reviewed Articles: It offers access to high-quality, peer-reviewed literature from medical journals.

  • LinkOut: MEDLINE articles often link to the full-text versions of articles if they are available.

  • MeSH Terms: MEDLINE uses Medical Subject Headings (MeSH), a controlled vocabulary for indexing articles. This allows for precise searching of terms related to specific medical topics.

PubMed is a free platform that provides access to MEDLINE and other NLM resources, which makes it an invaluable tool for conducting health-related literature searches.

Health Planning and Administration Databases

For health systems research, planning, and administration, specialized databases are available that focus on policy, management, and public health issues.

Health Planning and Administration Databases:

  • Health Systems Research Database: Provides information on the management of health systems, policy research, and healthcare infrastructure development.

  • CINAHL (Cumulative Index to Nursing and Allied Health Literature): Focuses on nursing, healthcare administration, and allied health disciplines, offering journals, reports, and dissertations.

These databases are especially important for those studying healthcare administration, policy-making, and the organizational aspects of health systems.

Sequences Databases

Sequence databases are especially important for bioinformatics and molecular biology research. These databases provide access to a vast array of biological sequences, such as DNA, RNA, and protein sequences.

Examples of Sequence Databases:

  • GenBank: A comprehensive database of publicly available genetic sequences.

  • UniProt: A database of protein sequence and functional information, offering detailed descriptions of proteins in different species.

  • BLAST (Basic Local Alignment Search Tool): A tool to search for sequence similarities between your query and sequences stored in various biological databases.

These databases are crucial for researchers in genetics, genomics, and bioinformatics.

United Nations Databases

The United Nations (UN) provides a wealth of data and reports on global health issues, economic development, and public policy. These reports can offer important contextual data for your research, particularly in public health and international development studies.

UN Databases Include:

  • UN Data: Provides statistical data on a wide range of topics, including health, environment, education, and demographics.

  • UNICEF Data: Focuses on child health and development indicators globally.

  • World Health Organization (WHO) Reports: The WHO is an agency of the UN that provides up-to-date research on global health trends, policy guidelines, and best practices for improving health systems.

These databases are invaluable for health researchers who focus on global health, policy, or public health systems.

Other Web Resources

Various other online resources, including governmental websites, NGOs, and independent research organizations, provide valuable data, reports, and publications that can inform your literature review.

Examples of Useful Web Resources:

  • World Bank: Offers reports and data on global health and economic development.

  • Centers for Disease Control and Prevention (CDC): Provides data on health trends, disease outbreaks, and public health initiatives.

  • National Institutes of Health (NIH): Offers a wealth of health research, clinical trial information, and other biomedical resources.

 

Search Engines for Health Research

  • Search engines are essential tools for quickly finding relevant information, but for specialized topics like health research, certain search engines and databases are particularly useful.
  • Below are the main search engines that are widely used by researchers, health professionals, and academicians to find biomedical, health, and clinical literature.

1. Google Scholar

  • Description: Google Scholar is a widely used search engine that allows users to search across academic articles, theses, books, conference papers, and patents.

  • Strengths:

    • Free Access: Provides free access to many academic articles, though some may link to paid sources.

    • Citations: Google Scholar also shows citation counts, helping researchers understand the impact of particular articles.

    • Wide Coverage: Covers various academic disciplines beyond just health, making it a great general academic search engine.

  • Limitations: Sometimes it includes less relevant articles that may not be peer-reviewed.

  • Website: Google Scholar

 

2. PubMed

  • Description: PubMed is a free resource developed and maintained by the National Library of Medicine (NLM). It provides access to a massive collection of biomedical literature and research articles.

  • Strengths:

    • Biomedical Focus: Specializes in life sciences and biomedical research, making it a leading source for health and medical literature.

    • Access to MEDLINE: PubMed provides access to MEDLINE, which includes over 30 million citations from biomedical journals.

    • Free Full Text: Many articles are available through PubMed Central (PMC), a free repository of full-text articles.

    • MeSH Terms: PubMed uses MeSH (Medical Subject Headings) for consistent and precise searches.

  • Limitations: It may not cover all non-biomedical disciplines, limiting its scope for interdisciplinary topics.

  • Website: PubMed

 

3. Scopus

  • Description: Scopus is a comprehensive abstract and citation database that covers a wide range of disciplines, including health sciences, medicine, life sciences, social sciences, and engineering.

  • Strengths:

    • Citation Analysis: Scopus provides advanced tools for citation analysis, allowing researchers to track the influence and impact of publications.

    • Broad Coverage: It indexes over 75 million items, covering journals, conference papers, patents, and books.

    • Collaboration Insights: Scopus provides insights into collaborative research trends.

  • Limitations: It requires a subscription for full access, which can be a barrier for some users.

  • Website: Scopus

 

4. Embase

  • Description: Embase is a biomedical and pharmacological database that is particularly useful for drug research, clinical trials, and toxicology.

  • Strengths:

    • Pharmacology and Drug Research: Provides extensive coverage of pharmacy, toxicology, and drug-related literature, making it essential for drug research and clinical medicine.

    • European and Global Literature: Embase is known for its European focus and offers unique coverage of non-English literature, making it a great complement to MEDLINE.

    • Abstracts Included: Embase provides abstracts, which help researchers quickly assess the relevance of a paper.

  • Limitations: Access to Embase typically requires a paid subscription through universities or institutions.

  • Website: Embase

 

5. Cochrane Library

  • Description: The Cochrane Library is a highly regarded resource for evidence-based health information. It specializes in systematic reviews and meta-analyses on the effectiveness of healthcare interventions.

  • Strengths:

    • Systematic Reviews: It provides access to systematic reviews of healthcare interventions, offering rigorous and high-quality evidence.

    • Evidence-Based Medicine: Perfect for evidence-based medicine (EBM) studies, it is the gold standard for systematic reviews in healthcare.

    • Free Access: Some parts of the Cochrane Library are open-access, but full access may require a subscription.

  • Limitations: Not as comprehensive in covering all biomedical disciplines as PubMed or Embase.

  • Website: Cochrane Library

 

6. Google

  • Description: Google is the most widely used general search engine. It is useful for locating a variety of information, including health-related data.

  • Strengths:

    • General Search: Best for finding websites, blogs, articles, and other types of public content related to health.

    • Widely Accessible: It’s free and easy to use for general searches, and it indexes most content on the World Wide Web.

  • Limitations: Less reliable for academic research compared to specialized databases like PubMed or Scopus. Information can be unverified, and it may include non-peer-reviewed sources.

  • Website: Google

 

7. Web of Science

  • Description: Web of Science is a research database that covers a wide range of disciplines, including biomedical sciences, social sciences, engineering, and more. It offers citation indexing and impact analysis tools.

  • Strengths:

    • Multidisciplinary Coverage: Provides access to articles in various academic fields beyond health research, making it useful for interdisciplinary research.

    • Citation Indexing: Like Scopus, it provides citation analysis tools that help researchers track the influence of articles over time.

    • Journal Impact Factor: Provides tools for assessing the impact factor of journals.

  • Limitations: Like Scopus, it requires a paid subscription for full access.

  • Website: Web of Science

 

8. BIOSIS Previews

  • Description: BIOSIS Previews is a database dedicated to biological sciences and health research, focusing on life sciences, medicine, and related disciplines.

  • Strengths:

    • Biomedical and Life Sciences: Provides in-depth information on life sciences, including biotechnology, pharmacology, and public health.

    • Global Coverage: Includes global literature, offering insights from international sources.

  • Limitations: Requires a paid subscription for full access.

  • Website: BIOSIS Previews

 

9. ResearchGate

  • Description: ResearchGate is a social networking platform for scientists and researchers to share and discuss their work.

  • Strengths:

    • Research Community: Allows direct access to researchers, enabling collaboration and sharing of academic publications.

    • Open Access: Many researchers upload full-text versions of their articles, providing free access.

    • Direct Communication: You can contact authors directly for more information on their research or to request copies of their papers.

  • Limitations: Not a traditional search engine, but a platform for sharing research. Some content may not be peer-reviewed.

  • Website: ResearchGate

 

10. Elsevier ScienceDirect

  • Description: ScienceDirect is a leading full-text scientific database offering journals and books in areas like biomedical sciences, healthcare, engineering, and more.

  • Strengths:

    • Comprehensive Journal Access: Provides access to a wide range of peer-reviewed biomedical literature.

    • Open Access: Some articles are available as open-access, providing free access to the public.

  • Limitations: Subscription-based access is required for many of the journals and articles.

  • Website: ScienceDirect

 

Automatic Term Mapping

  • Automatic Term Mapping (ATM) is a feature used by databases like PubMed and MEDLINE to improve search results.
  • ATM automatically maps user-entered search terms to the Medical Subject Headings (MeSH) terms, which are standardized for the medical field.
  • This process helps improve the accuracy and relevance of search results by ensuring that the correct subject headings are applied to your search terms.
  • For example, searching for “heart disease” may automatically map to “Cardiovascular Diseases” within MEDLINE’s indexing system, leading to more relevant results.

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