Experimental economics is the use of experimental methods to evaluate theoretical predictions of economic behaviour. It uses controlled, scientifically-designed experiments to test economic theories under laboratory conditions. Typical empirical research is limited by the fact that only a subset of the set of all possible influences affect (or can be observed to be affecting) economic decision making; therefore, the ability to control for certain influences is limited or non-existent. With experiments, economists can fix some inputs and measure the effects of other inputs in a way that allows ceteris-paribus comparisons.