blindning

Blindning is a term used in several Scandinavian languages to denote the practice known in English as blinding. In research contexts, blinding is the deliberate concealment of information about group assignment or treatment from participants, clinicians, or researchers to minimize bias that could affect outcomes.

Common levels include single-blind, where participants do not know which treatment they receive; double-blind, in which neither participants nor those administering the treatment know; and triple-blind, where participants, those administering the treatment, and those assessing outcomes are unaware.

Implementation methods include using visually identical treatments (placebos or sham procedures), centralized randomization, coded labels, and procedures to limit information flow during data collection and analysis. Unblinding may occur in emergencies or when knowledge is essential for participant safety.

Blinding is widely used in clinical trials of medicines and devices and in some areas of psychology and social research. It aims to reduce performance bias (differences in care) and detection bias (differences in outcome assessment). Its effectiveness depends on whether the blinding remains intact; unblinding events or noticeable side effects can compromise it.

Limitations and ethics: Blinding is not always feasible; some interventions are obvious or require special protective measures. Ethical considerations include informed consent and the need to balance blinding with patient safety; planned unblinding protocols and independent data monitoring committees are often used.

See also: blinding in experimental design, randomization, placebo, bias.