Table 2.

Strategies for Blinding Key Players in Behavioral Trials

Key Player	Strategy
Participant	• Keep available information general in nature.
	• Blind to design and hypotheses.
	• Use multiple (active) controls to limit bias.
	• Direct participants to not discuss group assignment.
Health care provider	• Blind to design, hypotheses, eligibility criteria, and outcomes.
	• Provide orientation and training according to manual of procedures.
	• Implement fidelity measures.
Data collector	• Blind to hypotheses, group assignment, purpose, and interventions.
	• Use objective outcome measures whenever possible.
	• Limit access to other study-related personnel or materials.
	• When interrater and test–retest reliability are strong, stagger data collectors, so that the effects of intervention are not readily apparent.
Principal investigator	• Limits contact with participants, health care providers, and data collectors.
	• Schedules study appointments after medical appointments.
	• Employs an independent statistician.
	• Develops rapid unblinding procedures.