How do we define abnormality and classify mental disorders?

Answer the questions UNDER the question to eliminate any confusion.

Also, each question is to be 200 or more words with all references and citation included with each question.

1.1 How do we define abnormality and classify mental disorders?

1.2 What are the advantages and disadvantages of classification?

1.3 How common are mental disorders? Which disorders are most prevalent?

1.4 Why do we need a research-based approach in abnormal psychology?

1.5 How do we gather information about mental disorders?

1.6 What kinds of research designs are used to conduct research in abnormal psychology?