Are observable and easy to measure, while are not so observable or easy to measure.

behaviors, mental processes

Explanation:

Behaviours observable and easy to measure, while mental processes are not so observable or easy to measure.

Human behaviours can be measured by three fundamental properties which include repeatability, temporal extent, and temporal locus. The ability to measure human behaviour is important as it helps to identify the function maintaining a problem behavior and to evaluate the success of a positive behavior support plan. On the contrary, mental processes such as perception, memory, thinking are not easily observable or measurable.

classical republicanism, also known as civic humanism, is a form of republicanism  developed in the renaissance inspired by the governmental forms and writings of  classical  antiquity, especially such  classical  writers as aristotle, polybius, and cicero.