In the world of investing, robust is a characteristic describing a model's, test's, or system's ability to perform effectively while its variables or assumptions are altered. A robust concept will operate without failure and produce positive results under a variety of conditions.

For statistics, a test is robust if it still provides insight into a problem despite having its assumptions altered or violated. In economics, robustness is attributed to financial markets that continue to perform despite alterations in market conditions. In general, a system is robust if it can handle variability and remain effective.