I am wondering if this question may have to do with the "eligibility criteria" involved in the particular study you're applying to.
Meaning: "Each study’s protocol has guidelines for who can or cannot participate in the study. These guidelines, called eligibility criteria, describe characteristics that must be shared by all participants. The criteria differ from study to study. They may include age, gender, medical history, and current health status. Eligibility criteria for treatment studies often require that patients have a particular type and stage of cancer.
Enrolling participants with similar characteristics ensures that the results will be due to what is under study and not other factors. In this way, eligibility criteria help researchers achieve accurate and meaningful results. These criteria also make certain that people who could be made worse by participating in the study are not exposed to the risk."
I wonder if they are looking for those who are suffering from migraine disease who have mostly been untreated or have, for example, chronic migraine attacks vs episodic migraine attacks. Or maybe they are looking to see if left untreated how long it takes to go from moderate to severe left untreated. I think this question is based on the basis of the study.
Do you have more info on what the basis or hypothesis of the study involves? Rebecca (comm advc)