Dr. faircloth is conducting a study of military veterans from the vietnam and gulf wars. he plans to evaluate them every year for 10 years to see if those with ptsd have a more pronounced decline in mental abilities and overall memory. this is a study.

Longitudinal Study - A longitudinal Study is research that is carried out over long periods of time, often decades. During this period, subjects (people) are studied through repeated observations to evaluate development trends across extended periods of time. Advantage of this method is that they are valuable in identifying patterns and trends over  time, ensure a clear focus and provide a high accuracy in detecting changes. However, this kind of research is very time consuming and expensive.