Which Threat to Internal Validity Is Controlled by Randomly Assigning

question 20

Multiple Choice

Which threat to internal validity is controlled by randomly assigning research participants to experimental conditions?

• A) selection
• B) history
• C) maturation
• D) testing
• E) attrition

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Definitions:

Corrugator Supercilii

A small, narrow muscle close to the eyebrow, responsible for drawing the eyebrow downward and medially, creating frown lines on the forehead.

Levator Palpebrae Superioris

A muscle in the orbit of the eye that elevates the upper eyelid, allowing the eye to open.

Orbicularis Oculi

A circular muscle around the orbit of the eye that enables blinking and closing of the eyelids.

Zygomaticus Major

A facial muscle that draws the mouth upward and outward, playing a key role in expressing smiling.