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Logic Modeling

Logic Modeling. Data flow diagrams do not show the logic inside the processes Logic modeling involves representing internal structure and functionality of processes depicted on a DFD Logic modeling can also be used to show when processes on a DFD occur. 9. 1. Logic Modeling.

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Logic Modeling

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  1. Logic Modeling • Data flow diagrams do not show the logic inside the processes • Logic modeling involves representing internal structure and functionality of processes depicted on a DFD • Logic modeling can also be used to show when processes on a DFD occur 9.1

  2. Logic Modeling • Deliverables and Outcomes • Structured English • Decision Tables • Decision Trees • State-transition diagrams • Sequence diagrams • Activity diagrams 9.2

  3. Modeling Logic with Structured English • Modified form of English used to specify the logic of information processes • Uses a subset of English • Action verbs • Noun phrases • No adjectives or adverbs • No specific standards 9.3

  4. Modeling Logic with Structured English • Similar to programming language • If conditions • Case statements • Figure 9-3 shows Structured English representation for Hoosier Burger 9.4

  5. Modeling Logic with Decision Tables • A matrix representation of the logic of a decision • Specifies the possible conditions and the resulting actions • Best used for complicated decision logic 9.5

  6. Modeling Logic withDecision Tables • Consists of three parts • Condition stubs • Lists condition relevant to decision • Action stubs • Actions that result from a given set of conditions • Rules • Specify which actions are to be followed for a given set of conditions • Indifferent Condition • Condition whose value does not affect which action is taken for two or more rules 9.6

  7. Developing Decision Tables Tutorial - http://www.mccombs.utexas.edu/courses/mis374/Bailey/Class20Chpt7PrelimConst/Class20Decision%20Table%20and%20Structured%20EnglishTutorial.doc • Determine the number of conditions that may affect the decision • Determine the number of possible actions that can be taken • Determine the number of condition alternatives for each condition • Calculate the maximum number of columns in the decision table by multiplying the number of alternatives for each condition

  8. Developing Decision Tables (cont.) • Fill in the condition alternatives

  9. Developing Decision Tables (cont.) • Combine rules where alternative conditions don’t affect the outcome

  10. Modeling Logic with Decision Trees • A graphical representation of a decision situation • Decision situation points are connected together by arcs and terminate in ovals • Two main components • Decision points represented by nodes • Actions represented by ovals 9.10

  11. Modeling Logic with Decision Trees • Read from left to right • Each node corresponds to a numbered choice on a legend • All possible actions are listed on the far right 9.11

  12. Figure 9-9Decision tree representation of the decision logic in the decision tables in Figures 9-4 and 9-5, with only two choices per decision point 9.12

  13. Deciding Among Structured English, Decision Tables and Decision Trees 9.13

  14. Summary • Several methods of logic modeling • Structured English • Primarily communication technique for analysts and users • Decision Tables • Conditions are listed in condition stubs • Possible actions are listed in action stubs • Rules link conditions with actions 9.14

  15. Summary • Decision Tables • Lists all possible rules • Decision Trees • Conditions are portrayed by decision points • Values are represented by paths between decision points and ovals that contain actions 9.15

  16. Summary • Comparison of Structured English, Decision Tables and Decision Trees • Most studies show that decision trees are best for many criteria • There is no best technique • Analyst must be proficient in all three 9.16

  17. Writing Instructions

  18. Examples of Actual Instructions • On a bag of Fritos – “You could be a winner! No purchase necessary. Details inside.” • Bar of Dial Soap – “Use like regular soap.” • Frozen dinner serving suggestion – “Defrost” • Hotel-provided shower cap in a box – “Fits one head”

  19. Examples of Actual Instructions • Tesco’s Tiramisu Dessert – “Do not turn upside down.” printed on the bottom of the box • Nytol (a sleep aid) – “Warning: may cause drowsiness” • Korean kitchen knife – “Warning: keep out of children.” • Sainsbury’s Peanuts – “Warning: contains nuts.” • Chinese-made Christmas lights – “For indoor or outdoor use only.”

  20. Instructions • Instructions are everywhere • Instructions have the power to get people to perform important actions • Good instructions create value

  21. Building Blocks of Actionable Instructions Good instructions contain the following: • Purpose (reason) • Objective (destination) • Core (procedure) • Time (duration) • Expectation (anticipation) • Failure (error)

  22. Example We’d like you to come to our house next Friday. (destination) We’re having a dinner party to celebrate our anniversary. (reason) Our address is 1015 Forest. Get off at the Oak Park exit on the Eisenhower Expressway. (procedure) The drive should take about 35 minutes in moderate traffic. (duration) On the expressway, you will pass Central Avenue and then Austin before you come to Oak Park. (anticipation) If you see the exit for River Forest, you’ve gone too far. (error)

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