Stratified sampling is often used when one or more of the stratums in the population have a low incidence relative to the other stratums. Convenience sampling is used in exploratory research where the researcher is interested in getting an inexpensive approximation of the truth.
Millions of Americans live with various types of mental illness and mental health problems, such as social anxiety, obsessive compulsive disorder, drug addiction, and personality disorders. Treatment options include medication and psychotherapy.
Mental illness is associated with increased occurrence of chronic diseases such as cardiovascular disease, diabetes, obesity, asthma, epilepsy and cancer. (CDC) Mental illness is associated with lower use of medical care, reduced adherence to treatment therapies for chronic diseases and higher risks of adverse health outcomes.