Which threat to external validity is controlled for in a double-blind experimental study? 1. ...

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Rationale 1: The Rosenthal effect is the influence of an interviewer on a subject's answers.
Rationale 2: The Hawthorne effect is a threat to external validity in a double-blind experiment because it occurs when subjects respond in a certain manner because they know they are part of a study.
Rationale 3: The experimenter effect occurs when the researcher's behavior influences the subject's behavior.
Rationale 4: Measurement effect occurs when subjects have been sensitized to the treatment by taking a pretest.
Global Rationale: