Consider the following statements about experimental research. Which of them are applicable?

1.The researchers randomly assign participants to groups

2.They provide control over extraneous variables to isolate the effects of the independent variable on the results

3.The treatment conditions may be physically manipulated

4.There is a statistical comparison of the groups

5.The experiment is designed to reduce threats to internal and external validity

A1, 2, 3 and 4

B2, 3, 4 and 5

C1, 3, 4 and 5

DAll of the above ✓ Correct

Correct answer: (D) All of the above

Explanation

Random assignment, control of extraneous variables, manipulation, statistical comparison and validity protection all apply to experiments.

Randomly assigning participants to groups balances them at the start.

Controlling extraneous variables isolates the independent variable's effect.

Treatment conditions may be physically manipulated by the researcher.

Groups are compared statistically, and the design guards internal and external validity.

These features together let experiments support causal claims.

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