Risk assessment can also be made on a much larger "systems" scale, for example assessing the risks of a nuclear power plant (an interactively complex mechanical, electronic, nuclear, and human system) or a hurricane (a complex meteorological and geographical system). Systems may be defined as linear and nonlinear (or complex), where linear systems are predictable and relatively easy to understand given a change in input, and non-linear systems unpredictable when inputs are changed As such, risk assessments of non-linear/complex systems tend to be more challenging