Creativity is a central question in economics, where it is known as ingenuity (the ability to come up with new ideas) or individual capital - capacities that individuals have, that do not arise from simple imitation of what is known already. This is separate from the instructional capital that might try to capture some of that in a patent or training system that helps others do what the individual leader or founder of the system can do. In urban economics there are various ways to measure creativity - the Bohemian Index and Gay Index are two attempts to do this accurately and predict the economic growth of cities based on creativity.