An Observational Study

question 16

Multiple Choice

An observational study

• A)analyzes data already available.
• B)makes it possible to rule out factors over which the researcher has no control for the observed effects.
• C)examines individuals that have been selected by the researchers.
• D)allows researchers to control for all extraneous factors.

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Definitions:

Visual Acuity

Visual acuity or the precision in seeing, often assessed by the capacity to recognize letters or numbers at a given distance.

Snellen Chart

A chart commonly used to measure visual acuity that consists of letters of progressively smaller size, used during eye examinations.

Near Vision Acuity

The ability to see clearly at a close range, typically measured to evaluate eyesight for reading and other close-up tasks.

Jaeger Chart

An eye chart used for reading up close and for determining near vision.