decision table
TRANSCRIPT
Decision Tables and Decision Trees
ByBhumika shah
Decision Table
---------------------------------------------------
Decisiontablesprovideawaytoexamine,describe, anddocument decisions using a table.
Theyareusedto
Describe the conditions
Identifypossible decision alternatives
Indicate actions should be performed, and
Describe actions
Decision Table
A matrix representation of the logic of a decision.
Specifies the possible conditionsand the resulting actions.
Best used for complicated decision logic.
Consists of three parts Condition stubs
Lists condition relevant to decision Action stubsActions that result from a given set of conditions Rules
Specify which actions are to be followed for a given set of conditions.
Decision Table Structure
---------------------------------------------------
Decision table for payroll system
---------------------------------------------------
Decision Table Types
Major2 types of Decision Table
Limited Entry Decision Table Yesor Noanswers to condition and action statements.
Extended Entry Decision Table Descriptive orin quantified form
Mixed Entry Decision Table Bothfixedandvariable entries
---------------------------------------------------
Advantages of Decision Table
Managers can be relieved from decision making for routine matters.
Complex decisions rules may be structured.
Consistency in decision making.
Communication between the manager and system analyst becomes easier.
A method of documentation that can be easily prepared, changed and updated
Summarized and standardized format, hence easier to use.
---------------------------------------------------
Disadvantages of Decision Table
---------------------------------------------------
Anadditional burden.
Doesnotdepict the flow by logic of asolution to a given problem.
Noteasy to translate it into source program.
Decision Trees
---------------------------------------------------
Decision trees are used when complex branching occurs inastructured decision process
Trees are also useful when it is essential to keepa string ofdecisions ina particular sequence
Drawing Decision Trees
---------------------------------------------------
First,identifyall conditions and actionsand the order and timingof these (if they are critical).
Second, begin building thetree from left to right while makingsureyouarecomplete in listing all possible alternatives before
moving over to the right.
Decision Trees
---------------------------------------------------
Decision Trees
---------------------------------------------------
Decision Tree Advantages
---------------------------------------------------
Three advantages are:
Theorder of checkingconditions and executing actions isimmediately noticeable.
Second, conditions and actions of decision trees are foundon some branches but not on others.
Third,decision trees are more readily understood by othersin theorganization.
Selectinga Structured DecisionAnalysis Technique
---------------------------------------------------
Use these guidelines:
Use decision tables when complex combination of conditions, actions, and rules are found or you require a method that effectively avoids impossible situations,redundancies, and contradictions.
Use decision trees when the sequence of conditions and action is critical or when not every condition is relevant to every action (the branches are different)
Comparing Tools
---------------------------------------------------
Criteria Decision Tables Decision Trees
Determining ConditionsandActions
Transforming
Second Best Best
Conditions and Actions Second Best BestintoSequence
Checking ConsistencyandCompleteness
Best Best
Thank You