A decision tree (or tree diagram ) is a decision support tool that uses a tree-like graph or model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. Decision trees are commonly used in operations research, specifically in decision analysis, to help identify a strategy most likely to reach a goal. Another use of decision trees is as a descriptive means for calculating conditional probabilities.


General

In decision analysis, a "decision tree" — and the closely-related influence diagram — is used as a visual and analytical decision support tool, where the expected values (or expected utility) of competing alternatives are calculated.

Decision trees have traditionally been created manually, as the following example shows:

Manual decision tree.jpg

A decision Tree consists of 3 types of nodes:-

1. Decision nodes - commonly represented by squares
2. Chance nodes - represented by circles
3. End nodes - represented by triangles

Decision-Tree-Elements.png

Drawn from left to right, a decision tree has only burst nodes (splitting paths) but no sink nodes (converging paths). Therefore, used manually, they can grow very big and are then often hard to draw fully by hand.

Analysis can take into account the decision maker's (e.g., the company's) preference or utility function, for example:

RiskPrefSensitivity2Threshold.png

The basic interpretation in this situation is that the company prefers B's risk and payoffs under realistic risk preference coefficients (greater than $400K -- in that range of risk aversion, the company would need to model a third strategy, "Neither A nor B").

Influence diagram

A decision tree can be represented more compactly as an influence diagram, focusing attention on the issues and relationships between events.

Factory2 InfluenceDiagram.png

Uses in teaching

Decision trees, influence diagrams, utility functions, and other decision analysis tools and methods are taught to undergraduate students in schools of business, health economics, and public health, and are examples of operations research or management science methods.

Advantages

Amongst decision support tools, decision trees (and influence diagrams) have several advantages:

Decision trees:

  • Are simple to understand and interpret. People are able to understand decision tree models after a brief explanation.
  • Have value even with little hard data. Important insights can be generated based on experts describing a situation (its alternatives, probabilities, and costs) and their preferences for outcomes.
  • Use a white box model. If a given result is provided by a model, the explanation for the result is easily replicated by simple math.
  • Can be combined with other decision techniques. The following example uses Net Present Value calculations, PERT 3-point estimations (decision #1) and a linear distribution of expected outcomes (decision #2):

Example

Decision trees can be used to optimize an investment portfolio. The following example shows a portfolio of 7 investment options (projects). The organization has $10,000,000 available for the total investment. Bold lines mark the best selection 1, 3, 5, 6, and 7, which will cost $9,750,000 and create a payoff of 16,175,000. All other combinations would either exceed the budget or yield a lower payoff.

Investment decision Insight.png

Perhaps the most common online interaction with decision trees is in the form of online navigation. For example, online shopping sites (Amazon.com, BestBuy.com, SurLaTable.com, Shopping.com and nearly all others) have a 'top-level' or 'primary' navigation bar visible from the home page and usually from all pages on the site. On BestBuy.com, this top-level menu includes the major categories: "TV & Video, Audio, Car & GPS, Cameras & Camcorders, Computers..." Click on a top-level category of the decision tree, and you see a secondary navigation menu. For computers: "Laptops, Netbooks, Desktops..." Each leads to a set of tertiary-level or third-level menus which also act as 'filters', as well as featured products.

See also

External links

  • 5 Myths About Decision Tree Analysis in Litigation
  • Decision Tree Analysis mindtools.com
  • Decision Analysis open course at George Mason University
  • Tutorial on decision tree
  • Extensive Decision Tree tutorials and examples
  • Cha, Sung-Hyuk; Tappert, Charles C (2009). "A Genetic Algorithm for Constructing Compact Binary Decision Trees". Journal of Pattern Recognition Research 4 (1): 1–13.  

References

    Desktop LED Christmas Tree - buy at Firebox.com

    Forget buckets and logs, this particular Christmas tree uses a 9V battery as its base. Granted it's small but with 16 flashing LEDs it's ideal for adding festive cheer to your desk

    ...

    Desktop Christmas Tree Freeware download and review ...

    Desktop Christmas Tree is a small, digital Tannenbaum for your desktop. It can optionally stay on t

    ...

    Desktop Christmas Tree technical details from Drive ...

    Desktop Christmas Tree product details - at SnapFiles ... Supported operating systems: Win95, Win98, WinME, WinNT 3.x, WinNT 4.x, Windows2000, WinXP, Windows2003, Windows Vista Starter ...

    ...

    multiDesk - How to use Desktop Tree

    Desktop Tree View: Back to Index: The concept of Desktop Tree is very simple. If shows you which window belongs to which desktop.

    ...

    Desktop Christmas Tree Software - Christmas Tree ...

    Desktop Christmas Tree Software collection at final download. A collection of eight Christmas trees to your desktop. If you like to stuff blinking lights, elfs or Christmas trees ...

    ...

    Download Desktop Xmas Tree, Desktop Xmas Tree Download

    Free Desktop Xmas Tree Download, Desktop Xmas Tree Download

    ...

    Get free Christmas tree for your desktop

    Pages. About Us; Contact Us; Download. All Desktop trees in single file; A collection of eight Christmas trees to your desktop. Installation No installation or un-installation ...

    ...

    Desktop tree Free Download

    Desktop tree Free Download,Desktop tree Software Collection Download

    ...

    Desktop Enhancements - Desktop Christmas Tree 1.3 - If ...

    If you have started redecorating your apartment for Christmas and New Year, you may want to do the same to your computer desktop. Get free Christmas tree for your desktop.

    ...

    Desktop Tree Makers - $5 Script Archive Community Forum

    Desktop Tree Makers Idea Exchange & Discussion ... Idea Exchange & Discussion Would you like to see a new script developed? Is there some improvement to TUFaT.com that you would like to ...

    ...