Questions: An investigator wants to determine if ear bud use is a causative agent for hearing loss. She examines a group of people with hearing loss and a group of people with no hearing loss and asks them both about their history of ear bud use. In this study, ear bud use is the: Outcome (dependent) variable B. Hypothesis C. Descriptor D. Predictor (independent) variable

The answer is D: Predictor (independent) variable.

Explanation for each option:

• Outcome (dependent) variable: This would be the variable that the investigator is trying to measure or predict, which in this case is hearing loss. Therefore, ear bud use is not the outcome variable.

• Hypothesis: A hypothesis is a statement that can be tested by scientific research. Ear bud use itself is not a hypothesis; rather, the hypothesis might be that ear bud use causes hearing loss.

• Descriptor: A descriptor is typically a characteristic or feature used to describe something. While ear bud use could describe a behavior, in the context of this study, it is not merely a descriptor.

• Predictor (independent) variable: This is the variable that is manipulated or categorized to see if it has an effect on the dependent variable. In this study, ear bud use is being examined to see if it predicts or causes hearing loss, making it the independent variable.

In summary, ear bud use is the predictor (independent) variable in this study.