4. Was the outcome accurately measured to Yes Can’t tell No
minimise bias?
HINT: Look for measurement or classification bias:
• Did they use subjective or objective measurements?
• Do the measures truly reflect what you want them to
(have they been validated)?
• Has a reliable system been established for
detecting all the cases (for measuring disease
occurrence)?
• Were the measurement methods similar in the
different groups?
• Were the subjects and/or the outcome assessor
blinded to exposure (does this matter)?