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.
Sometimes symptoms of a mental health disorder appear as physical problems, such as stomach pain, back pain, headache, or other unexplained aches and pains.
Signs and Symptoms of Mental Disorders(including bipolar disorder, depression, schizophrenia, anxiety disorders or schizophrenia): Looking at the lists above, consider all the symptoms that could be attributed to either poor mental health or addiction (depression, social withdrawal, moodiness, etc.).