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 nothing to be ashamed of. It is a medical problem, just like heart disease or diabetes. Mental illnesses are health conditions involving changes in thinking, emotion or behavior (or a combination of these). Mental illnesses are associated with distress and/or problems functioning in social, work or family activities. Mental illness is common. In a given year: