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.
Key facts. 1  There are many different mental disorders, with different presentations. 2  Mental disorders include: depression, bipolar affective disorder, schizophrenia and other psychoses, dementia, intellectual disabilities and developmental disorders including autism. 3  There are effective strategies for preventing mental disorders such as depression.