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 Disorders. Get the facts on common mental disorders, such as those related to anxiety, attention deficit, conduct, depression, schizophrenia, and trauma. The following are descriptions of the most common categories of mental illness in the United States. Anxiety Disorders.