What do you think of Comer’s (textbook) the definition of “abnormal” behavior and mental disorders?

What do you think of Comer’s (textbook) the definition of “abnormal” behavior and mental disorders? Do you find the current definition problematic? Why or Why Not?

If you were researching “abnormal” behavior, what research method might you find most useful and why (eg case study, correlation, experiment)? What challenges might you encounter while conducting your research?