S556 SYSTEMS ANALYSIS & DESIGN Week 6

Using Language to Focus Thought (cf., Wood, 1997) SLIS S556 2  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

Our Tool—Graphical Languages SLIS S556 3  Advantages of a graphical language:  a picture is worth a 1000 words

Our Tool—Graphical Languages SLIS S556 4  A picture reveals relationship to the whole  A diagram supports systemic thought and makes it possible to create a coherent design response

Work Models SLIS S556 5  Work models = a graphical language to capture knowledge about work  Models make concepts concrete, in order for the team to share and discuss ideas  Models can be used to communicate with clients

5 Work Models in Contextual Design SLIS S556 6  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

Flow Model (Beyer & Holtzblatt, 1998, p. 92, 93) SLIS S556 7  The work must be broken into parts  Different departments coordinate to get its work done  The flow model represents this communication coordination necessary to make work happen

Flow Model (B&H, p. 92) SLIS S556 8 U1 (Secretary) Worker Vendor Marketing manager - Produce proposal checks invoices Request to schedule meeting w/ president Bulletin board announcement Requires lots of 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

Flow Model Rules (B&H, p.91) SLIS S556 9  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

Flow Model Rules (B&H, p.91) SLIS S  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)

Flow Model Rules (B&H, p.91) SLIS S  Communication breakdowns are shown with a lightning bolt  Note: the flow model needs to capture how work is really done

Specifying Processes SLIS S  Structured English  is based on the logical constructs of: sequence selection iteration

Sequence Model (see B&H p.99) SLIS S  A sequence model represents:  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  A sequence model supply the low-level, step-by- step information on how work is actually done

Sequence Model SLIS S  A sequence model:  Starts with the intent and trigger for the sequence  Lists each steps in order  Note: any steps that cause problems are labeled with a lightning bolt

Collecting Sequences During an Interview SLIS S  Steps (an action or thought preceding an action)  The details of the tasks depend on the scope of the group e.g., writing a memo (Department level vs. task level vs. user-interface level)  Get more details rather than less

Collecting Sequences During an Interview SLIS S  Hesitations & Errors  When the users hesitates or makes errors, ask Qs to find out what s/he is thinking about  This is an opportunity for your system to do better!  Hesitations for a thinking task could reveal decision points in the process

Collecting Sequences During an Interview SLIS S  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

Collecting Sequences During an Interview SLIS S  Every sequence has a primary intent (see B&H p. 98), which applies to the whole sequence  There will be secondary interests  E.g., paying bills (primary intent), not overdrawing her account (secondary intent)

Sequence Model: Example SLIS S Intent: Hiring someone Trigger: someone quits Review her job Define candidates’ qualifications & job description Intent: 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 SLIS S 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 Customer Sales Stockroom Request service Take order Fill order Pay Deliver order Collect order

DECISION TABLE

Specifying Processes SLIS S  Structured English  is based on the logical constructs of: sequence selection iteration

Limited Entry Decision Table SLIS S  When a customer wants to purchase an item, different conditions determine the actions you should take.

Limited Entry Decision Table SLIS S  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

Limited Entry Decision Table Under $50YYNN Pays by check w/ 2 forms of ID YNYN Uses credit cardNYNY Ring up saleXX Call supervisor for approvalX Require a signature that matches one on the back of the card X SLIS S conditions actions

General Rule SLIS S  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 N 3

Mixed Entry Decision Table Regular customer? YYYNNN Order value $ > > 100 Free shippingXX Discount given 010 % 15%05%10 % SLIS S conditions actions

Decision Tree: Hiring an Info Architect SLIS S College degree Formal education in IA Practical exp in IA Action Job Applicant yes no yes no yes no Job offer Keep app yes no Keep app Reject yes no yes no yes no Keep app Reject

Exercise: Decision Tree/Table SLIS S  You are in a situation where going through job postings and deciding which jobs to apply for. Draw a decision tree or table with:  three conditions  three actions

Modeling SLIS S  What constitutes a good model?

Exercise: Flow Model SLIS S  Form 4 groups (5 people each)  Develop a flow model based on the case presented in Alter’s article