In a business, one makes a rational decision through a process of logical thought.
The beginning of this process is the setting of a goal that is to be achieved through the decision that you are making. For example, a business owner might need to start by deciding whether they want to gain market share or to make the highest possible profit. No rational decision can be made without a clear understanding of the goal that is to be achieved.
The next step is to figure out what variables are involved in the decision at hand. For example, a business owner might need to think about how much staffing to have at a restaurant or store at a given time as well as how much those staff members should be paid. At this step, the owner must determine which variables are relevant to the question at hand and which are not.
Finally, the decision maker must determine the actual answer to the question. The owner has to determine which combination of these things will (if this is their goal) yield the highest profit. By identifying the goal, identifying the possible relevant variables, and finally analyzing the data to determine the answer, a business owner makes a rational decision based on facts and not on emotions.