A search string for a systematic review is a structured combination of keywords, synonyms, and Boolean operators (AND, OR, NOT) designed to retrieve all relevant studies while minimizing irrelevant results.
Start with Your Research Question
Break your research question into core concepts using the PICO framework (Population, Intervention, Comparison, Outcome) or similar models. For example, if studying "effectiveness of mindfulness interventions for anxiety in college students," your concepts are: college students (population), mindfulness interventions (intervention), and anxiety (outcome).
Identify Synonyms and Related Terms
List all possible ways each concept might appear in the literature. For "college students," include: university students, undergraduates, postsecondary students, tertiary education students. For "mindfulness," consider: meditation, MBSR, mindfulness-based stress reduction, contemplative practice. Include both American and British spellings (e.g., "behaviour" and "behavior") and common abbreviations.
Apply Boolean Operators
- OR connects synonyms within a concept: (college students OR university students OR undergraduates)
- AND connects different concepts: (mindfulness OR meditation) AND (anxiety OR stress) AND (college students OR undergraduates)
- NOT excludes unwanted terms, but use sparingly as it may eliminate relevant studies
Use Wildcards and Phrase Searching
Truncation symbols (usually ) capture word variations: "meditat" finds meditate, meditation, meditative. Quotation marks ensure exact phrases: "systematic review" won't match "review of systematic errors."
Test and Refine
Run your string in one database and review the first 50 results. If you're getting too much noise—studies about meditation in elderly populations when you need college students—tighten your population terms. If you're missing key papers you know exist, add more synonyms or check their keywords for terms you overlooked. WisPaper's Scholar Search supports complex logic like "include mindfulness but exclude yoga interventions" and filters out 90% of irrelevant results automatically, which can significantly speed up this refinement process.
Document Everything
Record your final search string, the date searched, and the database used. Systematic reviews require full transparency so others can reproduce your search.
