Look at the example above, note the number of articles found during the S1-3 stages (over 1.5 million). Yet the final number found was 7. Never worry about the initial figure when using 'OR'. The idea is that this number is as high as possible which shows the breadth of the search. The final search ends up with 7 articles which is much more managable a may mean reading all the articles. Imagine if this number was much higher! Using the column on the left can help you quickly reduce this number in a transparent way. Such as:

• By Date

• Full Text

• Subject Major headings

• Publication 

• Databases.............And more.  

The point here is to rationalise why you are doing something. For example limiting the date is often used but rarely done with a rationale. If you cant rationalise it simply note it as a limitation to your strategy.

NB if you do this using the method above it simply adds it to your list:

Using the example above this would become:

S5 Date 2010 - present day

S6 Journals only

S7 The subject major headings used were........these act like standardised tags for categorising research content.

Part 2 Inclusion & Exclusion criteria

Using inclusion and exclusion criteria when searching the literature for a systematic or secondary review is crucial for several important reasons:

Ensuring Relevance: Inclusion and exclusion criteria help researchers define exactly what types of studies, publications, or data will be considered in their review. This ensures that only the most relevant and appropriate sources are selected, maintaining the focus and quality of the research.

Reducing Bias: By establishing clear, predetermined criteria before beginning the literature search, researchers can minimize selection bias. This helps prevent cherry-picking studies that might support a predetermined conclusion and instead provides a more objective and comprehensive overview of the existing literature.

Improving Reproducibility: Explicit inclusion and exclusion criteria make the literature review process transparent and reproducible. Other researchers can understand exactly how studies were selected, which allows them to replicate the review or critically evaluate its methodology.

Managing Information Overload: Academic databases and research repositories often contain thousands or even millions of publications. Inclusion and exclusion criteria help researchers narrow down this vast amount of information to a manageable and meaningful subset of studies.

Maintaining Scientific Rigor: By carefully defining what studies will be included or excluded, researchers can ensure that only high-quality, methodologically sound research is incorporated into their review. This might involve setting criteria related to:

   - Study design

   - Publication date range

   - Language of publication

   - Specific research methodologies

   - Statistical significance

   - Peer-reviewed status

Focusing on Research Objectives: Inclusion and exclusion criteria help align the literature review with the specific research question or objectives. This ensures that the review remains focused and provides targeted insights relevant to the research goals.

Enhancing Systematic Approach: These criteria transform the literature review from a potentially haphazard process into a systematic, structured method of gathering and analyzing research evidence.

Exclusion criteria might include:

- Case studies

- Non-peer-reviewed publications

- Studies with significant methodological flaws

- Research conducted on animal models

By establishing and rigorously applying such criteria, researchers can conduct more comprehensive, reliable, and meaningful literature reviews that provide valuable insights into the current state of knowledge in their field.

Part 3 PRISMA diagram

The final part to a transparent search strategy would be to create a flow diagram. Here are a few examples:

• PRISMA Flow Diagram: This refers to a specific type of flow diagram recommended by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. It's a standardised way to visualise the search process for systematic reviews, particularly in healthcare research.

• Search Strategy Flow Diagram: This is a more general term encompassing any flow diagram that documents a search strategy. It's not limited to systematic reviews and can be used for various research projects.

Here's an example: