Boolean Search Guide

AND  — Narrows results. Both terms must appear.
       "machine learning" AND "drug discovery"

OR   — Broadens results. Either term may appear.
       "deep learning" OR "neural network"

NOT  — Excludes results. Removes records containing the term.
       cancer NOT "lung cancer"

()   — Groups terms to control evaluation order.
       (COVID-19 OR SARS-CoV-2) AND (vaccine OR vaccination)

# Ambiguous (results depend on database precedence):
sleep disorders OR insomnia AND cognitive performance

# Clear (intended meaning explicit):
(sleep disorders OR insomnia) AND cognitive performance

*  — Truncation (unlimited characters)
     therap*  matches therapy, therapies, therapeutic, therapeutics

?  — Single-character wildcard
     wom?n  matches woman, women

$  — Optional character (some databases)
     behavio$r  matches behavior, behaviour

PubMed:
  "machine learning"[Title]
  "Smith J"[Author]
  "Nature"[Journal]
  "2020/01/01"[Date - Publication] : "2024/12/31"[Date - Publication]

Web of Science:
  TI=("deep learning")
  AU=(Smith, John)
  SO=(Nature)
  PY=(2020-2024)

Scopus:
  TITLE("deep learning")
  AUTH(Smith)
  SRCTITLE(Nature)
  PUBYEAR > 2019

def build_pico_search(population: str, intervention: str,
                      comparison: str, outcome: str) -> str:
    """
    Construct a Boolean search string from PICO components.

    Args:
        population: Target population terms (OR-separated)
        intervention: Intervention terms (OR-separated)
        comparison: Comparator terms (OR-separated, may be empty)
        outcome: Outcome terms (OR-separated)

    Returns:
        Complete Boolean search string
    """
    blocks = []

    blocks.append(f"({population})")
    blocks.append(f"({intervention})")

    if comparison:
        blocks.append(f"({comparison})")

    blocks.append(f"({outcome})")

    return " AND ".join(blocks)


# Example: Effect of mindfulness on anxiety in college students
query = build_pico_search(
    population='"college students" OR "university students" OR undergraduates',
    intervention='mindfulness OR "mindfulness-based stress reduction" OR MBSR',
    comparison='"wait list" OR "waitlist" OR "usual care" OR "control group"',
    outcome='anxiety OR "generalized anxiety" OR GAD OR "anxiety symptoms"'
)
print(query)

1. Identify key concepts from your research question
2. List synonyms, related terms, and variant spellings for each concept
3. Combine synonyms within each concept using OR
4. Connect concept blocks using AND
5. Test the search in your target database
6. Review the first 50 results for relevance
7. If recall is too low: add more synonyms, use truncation
8. If precision is too low: add more AND blocks, use field limits
9. Document the final search string with date and result count

Language:        English, Chinese, Spanish, etc.
Date range:      Publication year or date added
Document type:   Journal article, review, conference paper
Study design:    RCT, cohort, case-control (PubMed clinical queries)
Species:         Human, animal (PubMed)
Open access:     Free full text available

# Therapy/Intervention (sensitive):
AND (randomized controlled trial[pt] OR controlled clinical trial[pt]
OR randomized[tiab] OR randomly[tiab] OR trial[tiab])

# Diagnosis (specific):
AND (sensitivity and specificity[MeSH] OR predictive value of tests[MeSH]
OR accuracy[tiab])

# Systematic Reviews:
AND (systematic review[pt] OR meta-analysis[pt] OR systematic[sb])