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Elicitation I Elicitation I

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• Another Definition for Requirements:– An externally Observable Characteristic of a

Desired System

• 2 Buttons in a mouse– If the user needs 2 buttons this is a requirement– If the user only need a way of moving slides

back and forth, this is too detailed to be a requirement

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Tackling the problem not the solution

My Elevator is too slow• My Elevator is slow

•You have a throughput problem not a speed problem !

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Tackling the problem not the solution

My Elevator is too slow

• Well it’s a problem because people complaint about the lines •As better as needed for stopping complaints

•Why is that a problem ?•How better should it be?

•How About Adding mirrors to the wall ?

• My Elevator is slow

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Context

• The Blank Page Illusion

• The Completeness Illusion

• Social Aspects Involved

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Why do We Need Requirements Engineering?

von Neumann:

“There is no sense in being precise when you don’t even know what you are talking about”

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Basic Needs for Elicitation

(Questions from Polya)

• What is unknown?

• Do you know any related problem?

• Can you reinvent the problem?

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Elicitation

Elicit [Var. elicit + make it clearer + extract]1.discover, make explicit, get as much information

as possible to understand the object being studied.

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Elicitation

• Identify sources of information

• Gather facts

• Communication

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Identifying Sources of Information

• Actors in the Universe of Discourse – Clients– Users– Developers

• Documents• Books• Software Systems• COTS

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Who is related to the software?

interested

customer

developers

users

clients

OwnerEspecialist

Hired

Partner

Third party clients

Investor

Quality Control (QC)Technical writers

Software Engineer

clients

Non-clients

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Criteria

• Experience

• Knowledge about the domain

• Volume of investment

• Function

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Sources of Information

UofD

UofDSource of Information = { a,b,c,d,e,f} U {g,h}

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Heuristics to identify sources of information

• Who is the client?• Who owns the system?• Is there any customized system available?• What are the books related to the

application?• Is it possible to reuse software artifacts? • What are the documents most cited by the

actors of UofD?

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Abstract tree of people interested in the software

CFO

Accounting Manager

Acquisition Sales

Revenue Manager

Emplyee A Employee B

•requirements

•requirements •requirements

•requirements •requirements

•requirements

•requirements

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Facts gathering• Document Reading• Observation• Interviews• Reunions • Questionnaires• Anthropology• Active participation from actors• Protocol Analysis• Reverse Engineering• Reuse

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Enterviews Interviews

• Structured– Usually 1 to 1– Can be 1 to n or n to 1– Requires some knowledge about the problem to

formulate the questions

• Tape it ?

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Structured Interview

• What to ask– Objective questions with precise target– One question should be related to the other

• How to ask

• Ask whom

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Non-Structured Interview

• More flexible– But still with a pre-defined guideline of

questions

• Informal– But always keep control

• Mostly used during exploratory phases– Sometimes interesting to be used later also to

solve conflicts or to further explore alternatives

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Tacit Knowledge

• The kind of knowledge that is trivial for the actor being interviewed but not for the interviewer

• Because it is trivial, people almost never remebers to mention it. The interviewer in his/her turn, not knowing about the tacit knowledge can not ask about it.

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The Interview Process

Prepare

Carry out

Follow up

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Interviews

• Follow Up – Essential – After the interview write down what you

understood– Send it to the user(s) involved and ask for a

feedback (Have I got it right?)– Ask if the user(s) want to add anything

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Interviews

• +– direct contact with the actors– Can validate information immediately

• -– Tacit knowledge– Cultural diferences

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Reading

• Books– Summary per chapter– Highlight the most important parts– Use a key-word index– vocabulary

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Reading

• Macrosystem Documents (A more careful reading)– Underline repeated words

– Synonymies

– Take note of unknown terms

– Search for relationships among terms

– Vocabulary

– Try to understand and document the structure of the documents

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Reading

• Macro system Documents – Understand the structure of the documents– How they relate/point to each other

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Reading

• Reading Similar Documents:– Identify structures– Relate structures – vocabulary

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Document Reading

• +– Easy access to different sources of information

– Volume of information

• -– Information can be very dispersed

– Considerable amount of work is required to identify relevant facts

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Questionnaires

• What should one ask ?– Asks for some knowledge about the problem

• Therefore you should have a minimum understanding about the problem

– similar to the structured interview

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QuestionnairesTypes• qualitative

– Allows the one answering to further considerations– Makes a later analysis more difficult– Control questions – We can stimulate conflicts in order

to verify the consistency of what is being told

• quantitative– grading ( Yes, No/ Good, mdeium, bad/ 0,1,2,3,4)– Question has to be well formed to allow a good

distribution of the answers

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Examples

• Quantitative

05

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5. A XXX mantém dados estatísticos sobre o processo de desenvolvimento de software?

SIMNÃO

5 - XXX keeps statistical data about the software development process

Nu

mb

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f A

nsw

ers

No Yes

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Examples

05

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Nu

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esp

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as

1 2 3 4 5

8. Durante o processo de produção é verificada uma alteração nos requisitos. Esta alteração:

(Não é registrada) (É registrada, mas não no documento de requisitos)

(É registrada formalmente no documento de requisitos)

8 – How easyly can you retrieve information from Patient’s Medical Records ?

Nu

mb

er o

f A

nsw

ers

Not easy at all Kind of easily easily

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Examples

• QualitativeHow do you see your background regarding the

development of quality software? What do you think would be necessary to improve your performance? What knowledges would like to get? Why ?

– Objective: verify the opinion regarding training policy

– Why ?: A mature organization has to have well defined training policies. Control question.

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Questionnaires

• +– Standard questions– Statistical treatment possible

• -– Answers are constrained– Few or no interaction/participation– Number of questionnaires returned can be

disappointing

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Meetings• An extension of an interview or

• Direct and Intense participation– Short and intense periods– focus

• Brainstorm

• JAD

• Requirements Workshop – Uses facilitators– Previous planning

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Meetings

Requirements Workshop

• Preparation– Adequate place– Choosing Participants– Prepare the material ahead– agenda

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Meetings

Requirements Workshop

• Facilitator– Trained– Team spirit– Respected by all participants– “Powerful” enough to make decisions when

conflicts arise

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Meetings

Requirements Workshop • During the meeting

– relax participants– Focus on ideas not people– Be open to brainstorming – Register the meeting (minutes are highly

desirable)

– follow up e agenda for next meetings

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Meetings

Requirements Workshop

• Problems– People with a reign attitude– Passive attitude– People arriving late– Negative/mocking comments– It is always hard to resume a meeting after a

disruptive interruption

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Meetings

Brainstorm• Generate and condensate ideas• Frequently, the best ideas are combinations

of two or more ideas• Prioritize the ideas • It is better to be done locally, but it is

possible to have it over the web or using video-conference

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Meetings

Brainstorm

Phase I – Generating ideas• Goal: Generate the more ideas possible

• Rules– Do not allow critics or debate at this point– Let the imagination flows– Change and combine ideas

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MeetingsBrainstormPhase II –Reducing the number of ideas• Discard ideas that are not worth to invest• Group ideas – make meaningful names and group

ideas according them• Anotate small descriptions about the rationale

regarding the ideas and its authors• Prioritize

– vote

– categorize - critical, important, useful

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Meetings

JAD (Joint Application Design)

Involves• Objectives• System Requirements• External Project

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Meetings

Principles of JAD

• Group dynamic• Visual resources• Organized and rational process• Documenting using the idea of “What you see is

what you get” (WYSISYG)

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Meetings

JAD

Target• Identify high level (abstract) requirements• Define and Associate the scope• Plan the activities for each phase of the project• Post and approve resulting documents

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Meetings

JAD’s Phases

• Customization• Meetings

– Present the tasks

– Join ideas

– Evaluate

– Compromise

• Closing

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MeetingsJAD - Documents

Requirements– High level requirements

– Goals

– Anticipated benefits

– Strategies and future considerations

– Hypothesis and constraints

– Security, auditing and control

– System scope

– System users and their locations

– Functional areas outside the application

•

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Meetings

JAD - Documents

Plans:– Participant matrix

– Identification of the JAD/PROJECT

– Estimative

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JAD

• Used to speed up the investigation of system requirements, design a solution, define new procedures

• Critical Factor : To have ALL the relevant participants present

• Typically used for 3-6 months long projects.– Larger projects may require one JAD at the

beginning of each iteration

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Meetings

• +– Gives the RE multiple options– Collective work

• -– Dispersion– Cost

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Observation

• To watch people while they’re doing their jobs

• Take careful notes

• Be careful about Taping/Recording

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Observation

• +– low cost– Easy task (Not always)

• -– Depends on the actor not being influenced

because he knows he’s being observed– Depends on the observer’s skills– Tends to be superficial due to the weak

exposition to the UofD

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Protocol Analysis

• Analyze the work the person “besides” you is doing

• Speak loud during the tasks• Some people claim during an interview one

can use the memory instead of what he/she really does

• Goal – identify the rationale used to perform a task

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Protocol Analysis

• +– Elicit facts not shown

• Easier to avoid tacit knowledge

– Better understanding about tasks and rationales behind them

• -– Focus on performance (not necessarily true)– Not always what I say is what I do !!!– May be hard to use in some environments (e.g.

hospitals)

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Ethnography

• Deeply integrate to the environment

• The Analyst becomes a client or even the responsible for some tasks

• Slow

• Long Term results

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Ethnography

• +– Focus from the inside to the outside– Contextualized

• -– Time– Lack of systematization