For the article below what are the independent, dependent, mediating and moderating variables?

New research shows that attractive lawyers earn more money than their less attractive colleagues, adding weight to earlier studies that have showed that good-looking people get ahead faster.... The recent study charted the careers of 2,500 students from a U.S. law school. A panel of independent raters examined the graduation year-book photos of the students and rated their appearance on a scale from 1 to 5. After using statistical methods to control for other factors such as intelligence as well as the size of the law firm where they were employed and whether the firm was located in a major metropolitan area, the researchers concluded that appearance was linked to pay. Five years after graduation, people of above-average attractiveness were earning 8% to 9% more than people of below-average attractiveness. The difference in earnings between attractive lawyers and their less attractive colleagues was much greater in the private sector than in the public sector.