Answer:
Step-by-step explanation:
Hypothesis: Increased levels of stress result in increased frequency of headaches.
We would use an experimental study to test this hypothesis because it allows us to manipulate the independent variable (stress levels) and observe its effect on the dependent variable (frequency of headaches).
Independent variable: Stress levels
Dependent variable: Frequency of headaches
Experimental group treatment: Participants in the experimental group would be subjected to a stress-inducing situation or task.
Control group treatment: Participants in the control group would not be subjected to the stress-inducing situation or task and would instead be in a relaxed state.
To avoid bias in the experiment, both the experimental and control groups should be similar in terms of age, gender, and any other relevant characteristics, and the administration of the stress-inducing task and the measurement of headache frequency should be standardized for both groups. Additionally, the participants should be blind to the purpose of the experiment to eliminate any placebo effects.