Question

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Explanation:

Identify the variables in the study

Using the Explanatory Variable and Response Variable knowledge points

• Explanatory Variable (Independent Variable): The factor being manipulated or investigated to see if it causes a change. Here, it is whether Polly takes the new medication.
• Response Variable (Dependent Variable): The outcome being measured to see if it responds to the explanatory variable. Here, it is the number of times she wakes up during the night.

Evaluate the given options

Using the Response Variable knowledge point

• Option 1: "How many times she wakes up overnight is the explanatory variable." (Incorrect, this is the measured outcome/response).
• Option 2: "The new medication is the response variable." (Incorrect, the medication is the explanatory variable).
• Option 3: "The duration of her experiment is the response variable." (Incorrect, 8 weeks is a controlled study duration, not the measured outcome).
• Option 4: "How many times she wakes up overnight is the response variable." (Correct, as this measures the effect of the medication).

Answer:

• How many times she wakes up overnight is the explanatory variable.
• The new medication is the response variable.
• The duration of her experiment is the response variable.
• How many times she wakes up overnight is the response variable. (Correct answer)