Some people believe that money can buy happiness. Dr. Goodwin wants to determine whether paying people plays a role in their happiness. The level of money given to a subject would be considered to be the

I believe the answer is: independent variable

independent variable refers to the variables that are not influenced by other variables. In research, independent variables is often used as control groups in order to know whether they would give some sort of effect to the things that being researched on or not.