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 refers to all of the diagnosable mental disorders and is characterized by abnormalities in thinking, feelings, or behaviors. Some of the most common types of mental illness include anxiety, depressive, behavioral, and substance-abuse disorders. There is no single cause for mental illness.