Confidence votes 20.3K. There are two basic types of submarine screws. (Screw is the proper term here as propeller is applied to small craft.) One of the screws is built for silence, and the other is built for speed. Screws built for speed typically have fewer blades and the blades are wider to grab more water as the screw spins in the water.
Economic Definition of assumption. Defined. Term assumption Definition: An initial condition or statement that sets the stage for an analysis by abstracting from the real world. Assumptions are important to economic theories and economic analysis. Some assumptions are used to simplify a complex analysis into more easily manageable parts.
Sam Ouliaris of IMF has this nice description of the enigma of economics â its models. The idea behind model ironically is to simplify economics: An economic model is a simplified description of reality, designed to yield hypotheses about economic behavior that can be tested. An important feature of an economic model is that it is necessarily subjective in design because there are no objective measures of economic outcomes. Different economists will make different judgments about what is needed to explain their interpretations of reality.