Blind

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A blind or blinded experiment is an experiment in which information about the testШУУД ҮЗЭХ information
A blind or blinded experiment is an experiment in which information about the test that might lead to bias in the results is concealed from the tester, the subject, or both until after the test.[1] Bias may be intentional or unconscious. If both tester and subject are blinded, the trial is a double-blind trial. Blind testing is used wherever items are to be compared without influences from testers' preferences or expectations, for example in clinical trials to evaluate the effectiveness of medicinal drugs and procedures without placebo or nocebo effect, observer bias, or conscious deception; and comparative testing of commercial products to objectively assess user preferences without being influenced by branding and other properties not being tested. Blinding can be imposed on researchers, technicians, subjects, and funders. The opposite of a blind trial is an open trial. Blind experiments are an important tool of the scientific method, in many fields of research—medicine, psychology and the social sciences, natural sciences such as physics and biology, applied sciences such as market research, and many others. In some disciplines, such as medicinal drug testing, blind experiments are considered essential. In some cases, while blind experiments would be useful, they are impractical or unethical; an example is in the field of developmental psychology: although it would be informative to raise children under arbitrary experimental conditions, such as on a remote island with a fabricated enculturation, it is obviously a violation of ethics and human rights. The terms blind (adjective) or to blind (transitive verb) when used in this sense are figurative extensions of the literal idea of blindfolding someone. The terms masked or to mask may be used for the same concept; this is commonly the case in ophthalmology, where the word 'blind' is often used in the literal sense.