Blinding limits knowledge of group assignments during a study. A useful report tells you whose knowledge was restricted. Rather than treating “single” or “double” as a complete explanation, look for the roles involved: participants, people providing the intervention, outcome assessors or analysts.
Read beyond the label
A paper may describe a blinded outcome assessment even when participants know which group they are in. Copy the role-specific description into your notes. If the report gives only a short label, record the missing detail as a question instead of assuming every member of the study team was blinded.
Keep allocation separate
Randomisation and blinding are distinct design features. The first concerns assignment to groups; the second concerns knowledge of that assignment. A simple two-column note prevents one feature being mistaken for evidence of the other. Read the methods section for both.
Look for changes during the study
If the authors report that blinding was broken or could not be maintained, note when, why and which outcomes might be affected. Do not erase this information when shortening a summary. Equally, an openly described limitation is not itself evidence that every result is wrong.
Questions worth carrying forward
Who was blinded? At what stage? What information was withheld? Does the discussion identify limitations? Save the relevant page or section reference alongside each answer. This makes the note auditable and helps separate a reported method from your interpretation of it.
Use this checklist to read a paper, not to select personal treatment or design an experiment. Our guide to revisiting research reading explains how to preserve source references and open questions.
Sources
NCI: blinded study. NCCIH: minimising bias.
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