P   ("subject/Mesh term" OR "keyword")

AND

I ("subject/Mesh term" OR keyword)"

AND/OR*

C ("subject/Mesh term" OR keyword)  (there may not be a comparison)

AND

O ("subject/Mesh term" OR "keyword)"

*ANDing intervention and comparison will require that both aspects are represented in results

ORing intervention with comparison with return literature that represents either or both.

• High Sensitivity = Low Precision
• Recall/Sensitivity - the number of relevant reports divided by the total number of existing relevant reports
• Precision - the number of relevant reports divided by the total number of reports identified

• conference proceedings
• posters and poster abstracts
• presented papers/abstracts

Sources:

• Associations & Professional Organizations
• Bibliographies

for more information:  Gray Literature in Health and Biomedicine

Search Filters by Study Design (from Harvard Countway Library)

• Randomized Controlled Trials
• Controlled Clinical Trials
• Non-randomized/Observational Designs
• Tests of Diagnostic Accuracy