Information System Analysis and Design Chapter 9
Four major steps in building decision trees
1. identify the conditions 2. identify the condition alternatives 3. identify the actions 4. identify the action rules (in order)
List the four main problems that can occur in developing decision tables
1. incompleteness 2. impossible situations 3. contradictions 4. redundancy
List three reasons for producing process specifications
1. reduce ambiguity of a process 2. obtain a precise description of what is accomplished; usually included in a packet of specifications for the programmer 3. validate the system design
The two building blocks of Structured English
1. structured logic or instructions organized into nested or grouped procedures 2. simple English statements such as add, multiply, move, etc. (strong, active, specific verbs)
Unlike the decision tree used in management science, what doesn't the analyst's tree contain? A) decisions B) conditions C) outcomes D) actions
C) outcomes
Which of the following is not an example of a keyword for structured English? A) IF B) DO C) PERFORM D) IS LIKE
D) IS LIKE
What is the advantage of using structured English to communicate with people in an organization
Structured English can be taught to and hence understood by users in the organization, so if communication is important, structured English is a viable alternative for decision analysis
In which two situations should you use structured English?
Structured English is useful when there are many repetitious actions or when communication to end users is important
All the process specifications are consolidated and included in the specification packet given to the computer programmer.
TRUE
Besides the obvious advantage of clarifying the logic and relationships found in human languages, structured English has another important advantage as a communication tool.
TRUE
Business rules are the set of procedures, conditions or formulas that allow a corporation to run its business.
TRUE
Decision trees are most often drawn on their side, with the root of the tree on the left-hand side paper, branching out to the right.
TRUE
Decision trees are useful when it is essential to keep a string of decisions in a particular sequence.
TRUE
Decision Trees
used when complex branching occurs in a structured decision process; when it is essential to keep a string of decisions in a particular sequence.
In a decision table, ________ occur(s) when rules suggest different actions but satisfy the same conditions.
contradictions
What is the first step to take in developing a decision table?
determin the number of conditions that may affect the decision. The number of conditions becomes the number of rows in the top half of the decision table.
Process specifications are sometimes called ________, because they are a small portion of the total project specifications.
minispecs
Structured English can be more complex if blocks of (instructions) are ________ within each other to show hierarchy.
nested
In order to determine the human information requirements using a decision analysis strategy, what must the systems analyst determine?
objectives
Decision Tables
provide a way to examine, describe, and document decisions using a table consisting of four quadrants. They are used to: (1) describe the conditions (2) identify possible decision alternatives (3) indicate which actions should be performed (4) describe actions.
When structured decisions are not complex, an appropriate technique for analyzing the decision process is the use of ________.
structured English
What is one of the major advantages of decision tables over other methods of decision analysis?
tables help the analyst ensure completeness; it is easy to check for possible errors, such as impossible situations, contradictions, and redundancy
What are the main uses of decision trees in systems analysis?
trees are used mainly for identifying and organizing conditions and actions in a completely structured decision process
Which quadrant of the decision table is used for conditions? Which is used for condition alternatives?
upper-left contains the conditions; upper-right containts condition alternatives
When is a decision table most useful
when complex combinations of conditions, actions, and rules are found or you require a method that effectively avoids impossible situations, redundancies, and contradictions
When is a decision tree most useful
when the sequence of conditions and actions is critical or not every condition is relevant to every action
All the process specifications for the entire data flow diagram are consolidated and included in the specification packet given to the computer programmer.
FALSE
If communication is unimportant, structured English is a viable alternative for decision analysis.
FALSE
It is useful to combine conditions and actions when drawing decision trees.
FALSE
Iteration data dictionary entries become simple structured English statements in a sequence.
FALSE
Process descriptions may exist on a form but not within a CASE tool repository.
FALSE
Use structured English when complex combinations of conditions, actions, and rules are found.
FALSE
In which two situations are decision trees preferable?
The decision trees are preferable when the sequence of conditions and actions is critical or not every condition is relevant to every action.
One of the goals of producing ________ is to validate the system design, including the data flow diagram and the data dictionary
process specifications
Business rules include
1. Definitions of business terms 2. Business conditions and actions 3. Data integrity constraints 4. Mathematical and functional derivations 5. Logical inferences 6. Processing sequences 7. Relationships among facts about the business
Five conventions to follow when using Structured English
1. Express all logic in terms of sequential structures, decision structures, or iterations 2. Use and capitalize accepted keywords such as: IF, THEN, ELSE, DO, DO WHILE, DO UNTIL, PERFORM 3. Indent blocks of statements to show their hierarchy (nesting) clearly. 4. When words or phrases have been defined in the Data Dictionary, underline those words or phrases to indicate that they have a specialized, reserved meaning. 5. Be careful when using "and" and "or" as well as "greater than" and "greater than or equal to" and other logical comparisons.
What four elements must be known for an analyst to design systems for structured decisions
1. Identify the conditions 2. Identify the outcomes (condition alternatives) for each decision 3. Identify the actions 4. Identify the action rules.
Three Basic Computer Programming Constructs
1. Sequence 2. Selection (If-Else Conditional) 3. Iteration (Loops)
The data dictionary may be used as a starting point when creating structured English as follows
1. Sequenced (simple + between elements) data dictionary entries become simple structured English statements. 2. Selection (elements within [ ] brackets) data dictionary entries become IF...THEN...ELSE structured English statements. 3. Iteration (elements within { } braces) data dictionary entries become DO WHILE, DO UNTIL, or PERFORM UNTIL structured English statements.
Structured English is based on
1. Structured logic, or instructions, organized into nested and grouped procedures 2. Simple English statements such as add, multiply, move, and so on
What are three advantages of decision trees over decision tables:
1. the order of checking conditions and executing actions is immediately noticeable 2. conditions and actions of decision trees are found on some branches but not on others 3. decision trees are more readily understood by others in the organization
When creating process specifications, what needs to be done for manual tasks? A) Create well-defined procedures for employees performing the tasks. B) Replace them with automated processes C) Outline the decisions using a decision tree D) Nothing, they are not part of processing specifications
A) Create well-defined procedures for employees performing the tasks
When drawing the tree, systems analysts do not have to identify: A) all outcomes. B) all actions. C) the order. D) all conditions.
A) all outcomes
What is a way to examine, describe, and document structured decisions? A) decision table B) data flow C) data dictionary D) database
A) decision table
Running a section of code over and over again until some condition is met is an example of a: A) loop B) IF...THEN. C) DO... WHILE. D) decision table
A) loop
Which is not one of three main advantages of a decision tree over a decision table? A) more correct as a communication tool B) sequential structure of decision tree branches C) conditions and actions of decision trees are found on some branches D) more readily understood
A) more correct as a communication tool
Define what is meant by structured decision
An approach to identify alternatives, evaluate tradeoffs, and make decisions; a decision for which a representative model can be built or automated easily; usually involves specific & single objectives which are not difficult to achive
In order to use structured English, which convention is not advisable? A) Express all logic in terms of sequential structures, decision structures, case structures, or iterations. B) Blank a line and indent blocks of statements to show their hierarchy. C) Use and capitalize accepted keywords such as IF, THEN. D) Be careful when using "and" and "or."
B) Blank a line and indent blocks of statements to show their hierarchy.
When selection is indicated for elements in the data dictionary: A) a simple sequence of structured English statements is all that is necessary. B) an IF...THEN...ELSE structure must be present in the structured English statements. C) DO WHILE, DO UNTIL, or PERFORM UNTIL structured English statements must be included. D) a decision tree must be used to depict the logic.
B) an IF...THEN...ELSE structure must be present in the structured English statements.
Primitive process specifications are NOT produced for: A) processes that use decision trees. B) processes for which pre-written code already exists. C) processes that involve complex editing. D) All of the above.
B) process for which pre-written code already exists
Which of the following is not a goal of producing process specifications? A) to reduce the ambiguity of the process B) to reduce the time it takes for a process to run C) to obtain a precise description of what is accomplished D) to validate the system design
B) to reduce the time it takes for a process to run
Which of the following is not a problem when creating decision tables? A) impossible situations B) too many conditions C) redundancy D) contradictions
B) too many conditions
Which of the following is not a business rule? A) business conditions and actions B) user ethics C) logical inferences D) processing sequences
B) user ethics
When iteration is indicated for an element or group of elements in the data dictionary A)a simple sequence of structured English statements is all that is necessary. B)an IF, THEN, ELSE, structured must be present in the structured English statements. C)DO WHILE, DO UNTIL, or PERFORM UNTIL structured English statements must be included D)a decision table must be used to depict the logic
C) DO WHILE, DO UNTIL, or PERFORM UNTIL structured English statements must be included
Which is the correct choice? A) Use structured English when not every condition is relevant to every action. B) Use decision tables when communication to end users is important. C) Use decision trees when the sequence of conditions and actions is critical. D) Use decision tables when there are many repetitious actions.
C) Use decision trees when the sequence of conditions and actions is critical.
In order to build decision tables, what does the analyst not need to do? A) Eliminate any impossible situations. B) Simplify the table as much as possible. C) Determine the minimum size of the table. D) Eliminate inconsistencies.
C) determine the minimum size of the table
Which of the following is not a business rule? A) logical inferences B) mathematical and functional derivations C) programming language IF statements D) definitions of business terms
C) programming language IF statement
Which is structured English not based on? A) instructions organized into nested and grouped procedures B) simple English statements C) unstructured logic D) add, multiply, move, and so on
C) unstructured logic
Process descriptions may exist on a form or within a ________ repository.
CASE tool
Which of the following is not one of the three basic constructs used to code computer programs? A) sequence B) selection C) iteration D) computation
D) computation
Which of the following is NOT one of the main problems that can occur in developing decision tables? A) incompleteness B) impossible situations C) contradictions D) repetition
D) contradictions
In a decision table, contradictions occur when: A) an important condition is omitted. B) when the situation cannot occur because there are two or more conditions that cannot occur at the same time. C) identical sets of alternatives require the same action. D) rules suggest different actions but satisfy the same conditions.
D) rules suggest different actions but satisfy the same conditions.
In which two situations do decision tables work best?
Decision tables are useful when complex combinations of conditions, actions, and rules are found or you require a method that effectively avoids impossible situations, redundancies, and contradictions.
________ are used when complex branching occurs in a structured decision process
Decision trees
6) Process logic may be represented as: A) structured English. B) a decision table. C) a decision tree. D) a formula. E) All of the above.
E) all of the above
A square node indicates a condition, and a circle indicates an action.
FALSE
Process specifications are always produced for input and output operations, such as a read or write operation.
FALSE
The lower half of a decision tree contains the actions to be taken on the left and the rules for executing the actions on the right.
FALSE
The use of diagrams makes the decision tree more readable when one thinks of a circle as signifying IF when the square means THEN.
FALSE
Use decision tables when the sequence of conditions and actions is critical
FALSE
Use decision tables when there are many repetitious actions.
FALSE
Use decision trees when communication to end users is important.
FALSE
Use decision trees when not every condition is relevant to every decision.
FALSE
Use decision trees when there are many repetitious actions.
FALSE
Use decision trees when you require a method that effectively avoids impossible situations, redundancies and contradictions.
FALSE
Use structured English when not every condition is relevant to every action.
FALSE
When structured decisions are not complex, an appropriate technique for analyzing the decision process is the use of semistructured English.
FALSE
While process specifications produce a precise description of what is accomplished, they are not detailed enough to validate the system design.
FALSE
A data structure with optional elements contained in parenthesis or either/or elements contained in brackets will have a corresponding ________ statement in the process specification.
IF ...THEN ...ELSE
Structured English
It is an appropriate technique for analyzing the system when structured decisions are not complex
________, indicated by braces on a data structure, must have a corresponding DO WHILE, DO UNTIL, or PERFORM UNTIL structured English statement
Iteration
________ are created for primitive processes on a data flow diagram.
Process specifications
In drawing the tree, begin building from left to right while making sure you are complete in listing all possible alternatives before moving over to the right.
TRUE
In drawing the tree, identify all conditions and actions and the order and timing of these.
TRUE
In systems analysis, trees are used mainly for identifying and organizing conditions and actions in a completely structured decision process.
TRUE
It is important to develop decision tables in a logical, systematic approach.
TRUE
One major advantage of using decision tables over other methods is that tables help the analyst ensure completeness.
TRUE
Process logic may be represented as either structured English, a decision table, a decision tree, or a formula.
TRUE
Process specifications show the decision-making logic and formulas necessary to transform process input data into output.
TRUE
Selection data dictionary entries become IF...THEN...ELSE structured English statements.
TRUE
Use decision tables when complex combinations of conditions, actions, and rules are found.
TRUE
Use decision tables when you require a method that effectively avoids impossible situations, redundancies, and contradictions.
TRUE
Use decision trees when not every condition is relevant to every action (the branches are different).
TRUE
Use decision trees when not every condition is relevant to every action.
TRUE
Use decision trees when the sequence of conditions and actions is critical.
TRUE