What is the influence diagram?
The influence scheme is a simple visual method for describing relationships. It looks like a development diagram and usually contains shapes with text attached arrows. The influence diagram can describe the exact mathematical connection between the components, or it could only provide a rough overview of how the complex system fits together. The influence diagrams are remarkable because they are an effective way to visualize different results in the decision -making process; They show which variables can be directly influenced by the creator of the decision and which are strictly affected by external influences.
shapes in the influence diagram, called nodes, represent different types of variables. For example, if the scheme is preparing for the creators of the decision in the company, it will be clear which variables that this person has to influence and which of them will be determined by external factors. According to the convention, controlable decisions are displayed as rectangles; External uncertainty manifests itself as ovals ;; And the goals appear as diamonds, hexagons or octagons. DifferentTypes of arrows can represent information, causality or probability.
The decision -making process will lead to an effective effect. If the aim is to maximize a final variable such as output or profit, the diagram should clearly show how the decision will affect this variable. Ideally, the influence diagram should allow you to calculate, as likely to have a specific outcome by a particular decision.
Consider someone who is trying to model nuclear proliferation in the Middle East. Its model may contain events such as Iranian nuclear, the beginning of the Egyptian weapon program and the publication of Israeli nuclear weapons. The occurrence of any of these events may affect the expected probability of others. The Iranian weapon program can only affect Egypt directly, but also through its effects on Israel. The influence diagram could try to represent mthe ears of the American creator of politics. Each policy has a direct impact on the probable behavior of the countries involved, except for the secondary effects that could result from these behavior. Ideally, the policy creator would have the ability to see the final effects of each policy on results such as overall weapons or probability of conflict.
The concept of the influence diagram comes from the mathematical concept of the Bayes network. Bayesian modeling is trying to represent a large set of events with connected probability. This type of model allows the variables to have effects on each other that spread throughout the net.
Influence schemes - and Bayesian models - have basically replaced decision trees as calculations and decisions. The decision -making trees use constantly dividing branches to move from the starting point to one -year results. Formally, decision -making trees can often create the same result as diagrams of influence; However, they are usually much larger and require repetition withTejny element many times across branches. They are not as flexible as diagrams of influence and cannot effectively represent the loops of influence.