Total participation in the prison study eliminated self-selection bias.

Evidence

In an extraordinary level of cooperation encouraged by the wardens, every member of each of the three groups in each of the three penitentiaries participated in the study. Total participation removed any possible bias that could result from some refusals to take part in the study. — Albert Bandura, Moral Disengagement, 2028

Categorization

• DEEPTHINKING: Rare methodological note: studying execution teams requires wardens to compel total participation, an unusual leverage that shapes what we can know about moral disengagement.