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Botany: Literature Reviews

A guide for researchers of systematic and taxonomic botany, and those studying plant and fungal diversity.

what is

Not to be confused with a book review, a literature review surveys scholarly articles, books and other sources (e.g. dissertations, conference proceedings) relevant to a particular issue, area of research, or theory, providing a description, summary, and critical evaluation of each work. The purpose is to offer an overview of significant literature published on a topic.

Systematic reviews are reviews of high-quality randomized controlled trials often crucial to evidence-based medicine. Systematic reviews are common to all sciences where data are collected, published in the literature, and an assessment of methodological quality for a precisely defined subject would be helpful.

Literature and Systematic Review Resources

Annual Reviews
Each article provides essential primary research literature referenced within each topic.

BIOSIS Previews
Limit to literature reviews in left menu.
Coverage: 1926 - present

Cochrane Library
Databases of evidence to inform decision-making.
Coverage:  date varies | Some full text

Embase
Key resource for conducting systematic reviews and researching evidence-based medicine.
Coverage: dates vary

Steps: in a systematic review

Step 1: Framing questions for a review
The problems to be addressed by the review should be specified in clear, unambiguous and structured questions before beginning. Once the review questions have been set modifications to the protocol should be allowed only if alternative ways of defining the populations, interventions, outcomes or study designs become apparent.

Step 2: Identify relevant work
Search for studies, multiple resources should be searched without language restrictions. The study selection criteria should flow directly from the review questions and be specified a priori. Reasons for inclusion and exclusion should be recorded.

Step 3: Assessing the quality of studies
Quality assessment is relevant to every step of a review.

Step 4: Summarize the evidence
Data synthesis consists of tabulation of study characteristics, quality and effects as well as use of statistical methods for exploring differences between studies and combining their effects (meta-analysis).

Step 5: Interpret the findings
The risk of publication bias and related biases should be explored. Exploration for heterogeneity should help determine whether the overall summary can be trusted. Any recommendations should be graded by reference to the strengths and weaknesses of the evidence.

Components

Components: four stages:

  • Problem formulation—which topic or field is being examined and what are its component issues?
  • Literature search—finding materials relevant to the subject being explored
  • Data evaluation—determining which literature makes a significant contribution to the understanding of the topic
  • Analysis and interpretation—discussing the findings and conclusions of pertinent literature

Literature reviews should comprise the following elements:

  • overview of the subject, issue or theory under consideration, with the objectives of the literature review
  • Division of work into categories such as a particular position, against, or offering alternative theses entirely
  • Explanation of how each work is similar to and how it varies from the others
  • Conclusions are considered in the argument, convincing opinions, or the greatest contribution to the understanding and development of the research area.

In assessing each piece, consider:

  • Provenance - What are the author's credentials? Are the author's arguments supported by evidence (e.g. primary historical material, case studies, narratives, statistics, recent scientific findings)?
  • Objectivity—Is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
  • Persuasiveness—Which of the author's theses are most/least convincing?
  • Value—Are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

Definition and Use/Purpose
A literature review may constitute an essential chapter of a thesis or dissertation, or may be a self-contained review of writings on a subject.
In either case, it should:

  • Place each work in the context of its contribution to the understanding of the subject under review
  • Describe the relationship of each work to the others under consideration
  • Identify new ways to interpret, and shed light on any gaps in, previous research
  • Resolve conflicts amongst seemingly contradictory previous studies
  • Identify areas of prior scholarship to prevent duplication of effort
  • Point toward further research
  • Place one's original work (in the case of theses or dissertations) in the context of existing literature

The literature review itself, however, does not present new primary scholarship.

Literature Reviews: Standards

PRISMA: stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses. It is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses

Cochran: Cochrane Reviews are seen as exemplifying best practice in the quality of both their conduct and reporting. To maintain this position we need to improve and maintain the quality of our output as standards and expectations for systematic reviews increase generally; we also need to ens Cochrane Review Groups (CRGs) and all reviews. To this end we have undertaken within The Cochrane Collaboration to define Methodological Expectations for Cochrane Intervention Reviews (MECIR).

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