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Z556 Systems Analysis & DesignSession 5
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Announcement• Final specification document due date has changed:
• Not 5/1/2015, but 4/29/2015
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Using Language to Focus Thought (cf., Wood, 1997)• The language gives you a way to see:
• a framework for interpreting the things you observe and• a structure of understanding you can elaborate as you learn
more
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Our Tool—Graphical Languages
• Advantages of a graphical language:• a picture is worth a 1000 words
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Too Big to See Models
Too Small to See
reveals relationship to the wholesupports systemic thought
creates a coherent design response
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Work Models
• Graphical languages to capture knowledge about workVisual analysis , Complexity simplified, Focused understanding
• Make concepts concrete for team discussion“on the same page”
• Help communicate with clients Identification of breakdowns
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5 Work Models in Contextual Design
• Flow model• The communication and coordination
• Sequence model• The detailed work steps to achieve a goal
• Artifact model• Physical things to support the work
• Culture model• Constraints on the work caused by policy, culture, or
values• Physical model
• Physical structure of the work environment
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Flow Model (Beyer & Holtzblatt, 1998, p. 92, 93)
• Represents the communication coordination necessary to make work happen
• The work must be broken into discrete parts• How departments really coordinate work IL
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People and organization
are bubbles on the model, and are
annotated with their position &
responsibilities
Flow Model Rules (Beyer & Holtzblatt, 1998, p. 91)
Flow is indicated as arrows between bubbles
People and organization
are bubbles on the model, and are
annotated with their position &
responsibilities
Artifacts are shown in boxes on the line
Informal
comm
unication and
actions are written
without a box
Places appear as large boxes, annotated with their responsibilities
Automated systems and databases usually should not go on the flow (they are shown as a large box with responsibilities only when they act like a physical place or an automated person)
Communication breakdowns are shown with a lightning bolt
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Flow Model Rules (Beyer & Holtzblatt, 1998, p. 91)
People and organization are bubbles on the model, annotated with their position & responsibilities
Flow is indicated as arrows between bubbles
Artifacts are shown in boxes on the line
Informal communication and actions are written without a box
Places appear as large boxes, annotated with their responsibilities
Automated systems and databases usually should not go on the flow (they are shown as a large box with responsibilities only when they act like a physical place or an automated person)
Communication breakdowns are shown with a lightning bolt
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Flow Model (B&H, p. 92)
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U1(Secretary)
Worker
VendorMarketing manager- Produce proposal
checks
invoices
Request toschedule meetingw/ president
Bulletin board
announcement
Requires lotsof iterations
- Ensure bills paid on time
President
checks to sign
- Run the business -Meet w/ management
Request for clarification
Proposal to proof
- Invoice for services
Specifying Processes
• Structured English• is based on the logical constructs of:
• sequence• selection• iteration
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Sequence Model (see B&H p.96-
101)
• Supplies the low-level, step-by-step information on how work is actually done
• Starts with the intent and trigger for the sequence and then lists each step in order
• Four components:• the steps by which work is done• the triggers that start a set of steps• The intents that are being accomplished• The breakdowns that prohibit workers from being
efficient
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Sequence Model
Sequence Model – Steps
• An action or the thought preceding an action
• Details of the tasks depend on the scope of the group (e.g., writing a memo)
• Interview Tip: Get more details rather than less
Sequence Model - Trigger
What causes the sequence of actions(May be discrete event, based on time, or less tangible)
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Collecting Sequences During an Interview• Triggers (that cause the sequence of actions):
• may be discrete events, e.g.,???• may be based on time, e.g.,???• may be less tangible, e.g.,???
• The system needs a way to tell the user there’s something to be done IL
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Sequence Model
Sequence Model - Intent • Every sequence has a
primary intent, which applies to the whole sequence
• Secondary intent applies to individual or groups of steps
Sequence Model - Breakdown
Where are the problems in the sequence
• Interview Tip: Hesitations & Errors often show breakdowns.
• Interview Tip: Ask how the system could do better.
• Interview Tip: Hesitations while thinking reveal decision points in the process
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Sequence Model: Example
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Intent: Hiring someone
Trigger: someone quits
Review her job
Define candidates’ qualifications & job descriptionIntent:Review the current position
Advertise the job opening
Receive applications
Review applicants
Check references of selected candidates
Intent: Eliminate unqualified candidates
Fewer candidates to invite on site
Sequence Model: Example
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Set up interview dates with selected candidates
Choose the best candidate
Making a job offer
Negotiate
Candidate accepts the job Candidate denies the offer
Choose the 2nd best candidate
Intent: make decisions about which candidate
UML: Activity Diagrams— Example
http://www.uml-forum.com/tools.htm
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• Charts activity as it moves between different people/groups
• Liner like the sequence model, but articulates different players like flow model
Tools for Creating Diagrams• https://www.lucidchart.com/(good for collaboration)• http://www.gliffy.com/ (free for 5 diagrams)• http://www.diagram.ly/ • http://creately.com/ ($5/month)• https://cacoo.com/ (free plan included) • http://dia-installer.de/ (open source)• https://www.draw.io/
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Decision Table
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Specifying Processes
• Structured English• is based on the logical constructs of:
• sequence• selection• iteration
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Limited Entry Decision Table• When a customer wants to purchase an item, different
conditions determine the actions you should take.
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Limited Entry Decision Table
• First, identify the conditions:• Under $50?• Pays by check w/ 2 forms of ID?• Uses credit card?
• Next, identify the actions• Ring up sale• Call supervisor for approval• Require a signature that matches one on the back of the card
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Limited Entry Decision TableUnder $50 Y Y N N
Pays by check w/ 2 forms of ID
Y N Y N
Uses credit card N Y N Y
Ring up sale X X
Call supervisor for approval X
Require a signature that matches one on the back of the card
X
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conditionsactions
General Rule• Check the number of rules
• The number of answer: M (e.g., 2 for Y/N)• The number of condition: N
• M = M x M x M x M . . . (M to the nth power)• E.g., 2 = 2 x 2 x 2 = 8rules IL
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N
3
Mixed Entry Decision Table
Regular customer?
Y Y Y N N N
Order value $ 0-49
50-99
> 100
0-49
50-99
> 100
Free shipping X X
Discount given
0 10%
15% 0 5% 10% 27
conditionsactions
Decision Tree: Hiring an Info Architect
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Collegedegree
Formal education in IA
Practicalexp in IA
Action
JobApplicant
yes
no
yes
no
yes
no
Job offer
Keep app
yes
no
Keep app
Reject
yes
no
yes
noyes
no
Keep app
Reject Reject
Reject
Exercise: Decision Tree/Table
• This is your last semester at ILS, and you are ready to look for jobs. You need to go through job postings and decide which jobs to apply for. Draw a decision tree or table with:• three conditions• three actions
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Exercise: Flow Model
• Form 4 groups (5 people each)• Develop a flow model based on the case
presented in Alter’s article
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Modeling
• What constitutes a good model?
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