Blinding: ask who did not know which option was being evaluated

This glossary page uses that definition to introduce a reading question: who was kept unaware of which information, and when? It does not teach people to conduct clinical research or ask families to conceal treatment information from one another.

NIH's trial glossary also names single- and double-blind studies as single- and double-masked studies. [2] Here, masking refers only to that study terminology, not to the lived-experience meaning used elsewhere in the glossary.

A transparent, invented example

Imagine a community art activity with two proposed poster layouts. The contributors agree that a small judging group will see the layouts without the designers' names. The judges know the activity's purpose and what they are being asked to compare. The designs are marked A and B.

The names are withheld from the judges for this particular comparison. The organizer still knows who made each design, and the designers know their own work. Saying “nobody knew anything” would misdescribe the arrangement.

One judge recognizes a drawing style. The organizer can record that the judge may have inferred the designer instead of insisting the arrangement worked exactly as intended. This is an invented ordinary activity, not evidence that blinding always succeeds or that these designs were fairly evaluated in every respect.

Read the method beyond its label

What was being compared:
Information kept from view:
Who did not receive that information:
Who still knew it:
At what stage information became available:
Whether the report describes any difficulty maintaining that arrangement:
Question I still need answered:

When a research report uses a blinding label, look for its description of the people and stages involved. Do not infer all those details from one word in a headline. If only a summary is available, keep that limitation in your notes.

Separate blinding from the other methods

Blinding concerns what specified people know during a comparison. Random allocation concerns how assignments are made. A control group identifies a comparison arrangement. These questions can be asked separately; the art example does not establish that it used random allocation or a scientific control group.

Likewise, hiding a designer's name does not establish whether a layout is useful for every reader. The outcome being assessed and the way it was assessed remain separate questions.

What this means for a family reader

A teen can ask whose knowledge the study describes. A parent can look for whether the people recording an outcome knew the assignment. Partners can divide the task of locating that methods paragraph, while a grandparent can ask what information remained unavailable to the reader. No one needs to turn the household into an experiment to understand the term.

Source

[1] National Cancer Institute. Blinded study. NCI Dictionary of Cancer Terms. Publication date not stated on the inspected entry; accessed September 5, 2026. The clinical-study definition supports [1]. It does not validate the original art illustration, endorse a study, or establish a treatment recommendation.

[2] National Institutes of Health. Glossary of Common Terms. NIH Clinical Research Trials and You. Last reviewed January 17, 2025; accessed September 6, 2026. “Single- or Double-Blind Studies,” opening terminology equivalence, supports [2] only. No claims about bias prevention, trial participation, or treatment decisions are adopted.

Related guides

• Randomized controlled trial

  : distinguish allocation from knowledge of assignment.

• Control group

  : identify what is being compared.

• Peer review

  : keep manuscript review separate from study methods.

• Primary source

  : locate the actual method description.