Subject populations with circumstantial characteristics such as easy availability, compromised position, and susceptibility position, and susceptibility to manipulation make them susceptible to coercion and undue influence. Examples of such populations include students, employees of research institutions, prisoners, patients in mental institutions, patients with life-threatening conditions, and military personnel, all of whom may have subservient or dependent relationships of some kind to the investigator. Subjects may inappropriately be told that their jobs, promotions, or grades are contingent upon research participation. Additionally, if an investigator also serves as a patient's primary care physician, the patient may feel obliged to participate in the research to please and express gratitude, or out of fear that declining to participate in the study will result in resentment or abandonment.