University of Toronto University of Toronto Department of Computer Science Requirements Elicitation Lecture 3 Requirements Elicitation I Last Last Week Week Starting point Some notion that there is a problem that needs solving Approaches Approaches to to RE RE Processes Processes methods methods techniques techniques Domains Domains Systems Theory Systems Theory e g dissatisfaction with the current state of affairs e g a new business opportunity e g a potential saving of cost time resource usage etc Collect enough information to This This Week Week identify the problem opportunity Elicitation Elicitation I I Traditional Traditional approaches approaches Interviews Interviews Questionnaires Questionnaires Scenarios Scenarios Goals Goals and and Use Cases Use Cases Next Next Week Week University of Toronto University of Toronto The four worlds Which Which 3 Department of Computer Science Subject World e g customers accounts transactions for a bank information system Usage World the environment within which the planned system will operate Subject World e g people such as managers clerks customers also business processes such as handling a withdrawal a deposit of foreign currency Uses System World what the system does within its operational environment what information it contains and what functions it performs System World e g system records all transactions in a database reports on transactions for a particular account gives account balance builds Development World the development process team schedule required qualities security performance etc e g system to be delivered in 12 months fully tested to MCDC standard etc Development World Source Adapted from Loucopoulos Karakostas 1995 p73 Why Why When When How How the subject matter of the information system contracts What What Where Where Who Who Finding out about the four worlds Maintains information about Usage World The The journalist s journalist s technique technique 2000 2003 Steve Easterbrook Department of Computer Science Needs information about W6H W6H Learn how to find your way round a new problem area quickly Use your initial ignorance as an excuse to ask questions Recognise the domain expertise of the people you talk to 2 2000 2003 Steve Easterbrook Which problem needs to be solved identify problem Boundaries Where is the problem understand the Context Problem Domain Whose problem is it identify Stakeholders Why does it need solving identify the stakeholders Goals How might a software system help collect some Scenarios When does it need solving identify Development Constraints What might prevent us solving it identify Feasibility and Risk become an expert in the problem domain Elicitation Elicitation II II Cognitive Cognitive approaches approaches Contextual Contextual approaches approaches Ethnography Ethnography 2000 2003 Steve Easterbrook Department of Computer Science 4 2000 2003 Steve Easterbrook 5 1 University of Toronto University of Toronto Department of Computer Science Stakeholders Difficulties of Elicitation Stakeholder analysis Identify all the people who must be consulted during information acquisition Look for stakeholders associated with each of the four worlds Thin spread of domain knowledge The knowledge might be distributed across many sources It is rarely available in an explicit form I e not written down There will be conflicts between knowledge from different sources Example stakeholders People have conflicting goals People have different understandings of the problem Users concerned with the features and functionality of the new system Designers Tacit knowledge The say do problem People find it hard to describe knowledge they regularly use want to build a perfect system or reuse existing code Descriptions may be inaccurate rationalizations of expert behaviour Systems analysts want to get the requirements right Training and user support staff Limited Observability The problem owners might be too busy solving it using the existing system Presence of an observer may change the problem want to make sure the new system is usable and manageable Business analysts want to make sure we are doing better than the competition E g the Probe Effect and the Hawthorne Effect Technical authors will prepare user manuals and other documentation for the new system The project manager Bias People may not be free to tell you what you need to know wants to complete the project on time within budget with all objectives met Political climate organisational factors matter the customer People may not want to tell you what you need to know whoever it is that pays for the new system The outcome will affect them so they may try to influence you hidden agendas 6 2000 2003 Steve Easterbrook University of Toronto Department of Computer Science University of Toronto What The problem area Loan approval department in a large bank The analyst is trying to elicit the rules and procedures for approving a loan Implicit knowledge There is no document in which the rules for approving loans are written down Different members of the department have different ideas about what the rules are The loan approval process described to you by the loan approval officers is quite different from your observations of what they actually do Impression Impression management management of bias Motivational bias The loan approval process used by the officers while you are observing is different from the one they normally use the expert makes accommodations to please the interviewer or some other audience Bias The loan approval officers fear that your job is to computerize their jobs out of existence so they are deliberately emphasizing the need for case by case discretion to convince you it has to be done by a human Cognitive bias the expert does not follow objective rules or standards 8 Sources Sources of of Bias Bias We cannot perceive reality directly Types Probe effect Department of Computer Science Social Social pressure pressure All decision making is based partly on personal value systems Say do problem 2000 2003 Steve Easterbrook is bias It is interpreted through a filter of mental models mediated by our senses and neural pathways Conflicting information Expert Bias Bias only exists in relation to some reference point can there ever be no bias reflects reality or truth Why this might be difficult 7 2000 2003 Steve Easterbrook Example Department of Computer Science 2000 2003 Steve Easterbrook response responseto toverbal verbaland andnon verbal non