HCI121 VII Identifying needs and establishing requirements

• What, how and why?

  • What

  Two aims:

  1. Understand as much as possible about users, task, context

  2. Produce a stable set of requirements
• What, how and why?

  • How

  − Data gathering activities

  − Data analysis activities

  − Expression as ‘requirements’

  − All of this is iterative
• What, how and why?

  • Why

  − Requirement’s definition: the stage where failure occurs most commonly

  − Getting requirements right is crucial
• Establishing requirements

  • What do users want? What do users ‘need’?

  − Requirements need clarification, refinement, completion, re-scoping

  Input: requirements document (maybe)

  Output: stable requirements
• Establishing requirements

  • Why ‘establish’?

  − Requirements arise from understanding users’ needs

  − Requirements can be justified & related to data
• Different kinds of requirements

  • Functional:

  — What the system should do

  — Historically the main focus of requirements activities

  • (Non-functional: memory size, response time...)
• Different kinds of requirements

  Environment or context of use:

  — physical: dusty? noisy? vibration? light? heat? humidity? …. (e.g., OMS

  insects, ATM)

  — social: sharing of files, of displays, in paper, across great distances, work

  individually, privacy for clients

  — organisational: hierarchy, IT department’s attitude and remit, user support,

  communications structure and infrastructure, availability of training
• Different kinds of requirements

  • Users: Who are they?

  — Characteristics: ability, background, attitude to computers

  — System use: novice, expert, casual, frequent

  — Novice: step-by-step (prompted), constrained, clear information

  — Expert: flexibility, access/power

  — Frequent: short cuts

  — Casual/infrequent: clear instructions, e.g. menu paths
• Different kinds of requirements

  • Usability:

  learnability, throughput, flexibility, attitude
• Kinds of requirements

  What factors (environmental, user, usability) would affect the following systems?

  • Self-service filling and payment system for a petrol (gas) station

  • On-board ship data analysis system for geologists searching for oil

  • Fashion clothes website
• Data Gathering Techniques

  (1) Questionnaires:

  — A series of questions designed to elicit specific information

  — Questions may require different kinds of answers: simple YES/NO; choice of presupplied answers; comment

  — Often used in conjunction with other techniques

  — Can give quantitative or qualitative data

  — Good for answering specific questions from a large, dispersed group of people
• Data Gathering Techniques

  (2) Interviews:

  — Forum for talking to people

  — Structured, unstructured or semi-structured

  — Props, e.g. sample scenarios of use, prototypes, can be used in interviews

  — Good for exploring issues

  — But are time consuming and may be infeasible to visit everyone
• Data Gathering Techniques

  (3) Workshops or focus groups:

  — Group interviews

  — Good at gaining a consensus view and/or highlighting areas of conflict
• Data Gathering Techniques

  (4) Naturalistic observation:

  — Spend time with stakeholders in their day-to-day tasks, observing work as it

  happens

  — Gain insights into stakeholders’ tasks

  — Good for understanding the nature and context of the tasks

  — But it requires time and commitment from a member of the design team, and it can

  result in a huge amount of data

  — Ethnography is one form
• Data Gathering Techniques

  (5) Studying documentation:

  — Procedures and rules are often written down in manuals

  — Good source of data about the steps involved in an activity, and any regulations governing a task

  — Not to be used in isolation

  — Good for understanding legislation, and getting background information

  — No stakeholder time, which is a limiting factor on the other techniques
• Choosing between techniques

  Data gathering techniques differ in two ways:

  1.Amount of time, level of detail and risk associated with the findings

  2. Knowledge the analyst requires

  The choice of technique is also affected by the kind of task to be studied:

  — Sequential steps or overlapping series of subtasks?

  — High or low, complex or simple information?

  — Task for a layman or a skilled practitioner?
• Some basic guidelines

  • Focus on identifying the stakeholders’ needs

  • Involve all the stakeholder groups

  • Involve more than one representative from each stakeholder group

  • Use a combination of data-gathering techniques

  • Support the process with props such as prototypes and task descriptions

  • Run a pilot session

  • You will need to compromise on the data you collect and the analysis to be done, but before

  you can make sensible compromises, you need to know what you’d really like

  • Consider carefully how to record the data
• Data Interpretation and Analysis

  • Start soon after data gathering session

  • Initial interpretation before deeper analysis

  • Different approaches emphasize different elements e.g. class diagrams for object-oriented

  systems, entity-relationship diagrams for data intensive systems
• Task descriptions

  • Scenarios: an informal narrative story, simple, ‘natural’, personal, not generalizable

  • Use cases

  — assume interaction with a system

  — assume detailed understanding of the interaction

  • Essential use cases

  — abstract away from the details

  — does not have the same assumptions as use cases
• Task analysis

  • Task descriptions are often used to envision new systems or devices

  • Task analysis is used mainly to investigate an existing situation

  • It is important not to focus on superficial activities

  What are people trying to achieve?

  Why are they trying to achieve it?

  How are they going about it?

  • Many techniques, the most popular is Hierarchical Task Analysis (HTA)
• Hierarchical Task Analysis

  • Involves breaking a task down into subtasks, then sub-sub-tasks and so on. These are

  grouped as plans which specify how the tasks might be performed in practice

  • HTA focuses on physical and observable actions, and includes looking at actions not

  related to software or an interaction device

  • Start with a user goal which is examined and the main tasks for achieving it are identified

  • Tasks are sub-divided into sub-tasks