Many of the problems are of psychological nature and arise from undesirable patterns of behavior, negative attitude, and unhealthy thinking. Psychologists also design and carry out necessary intervention in the lives of the needy people to improve their quality of living. Thus there is no wonder that psychologists are working in a diverse number of fields such as the military, business corporations, schools, hospitals, industries, etc. Psychologists are also analyzing vital social problems relating to social change and development, population, poverty, interpersonal or intergroup violence, and environmental degradation.