Date : 6 Dec 2011
Requirement
What are Requirements?
A requirement is a statement that specifies what an intended product should do, or
how it should perform.
● Specific, unambiguous, clear
– Time to download any page is less than 5
seconds on a DSL line of 20Mbits/second
– The playback bar should always indicate the
position in the audio stream
● Too vague
– Appealing to teenage girls (too vague)
– The buttons should be engaging
Different kinds of requirement
● Functional
– Functional requirements specify what the system should do
– Historically the main focus of requirements
activities
– Examples: word processor must support variety of formatting styles, Calculate
total cost of purchases
● Non-Functional
– Non-Functional requirements specify what constraints there are on the system or its
development.
– Run on a variety of platforms
– Function on 64M of RAM
– Delivered in 6 months
*Interaction design requires us to understand both the functionality required and the
constraints for development or operation of the product.*
Different Requirements
● Environment or context of use
– Physical ( Dusty ? Noisy ? Vibrations ? Light ? Heat ? Humidity ? )
Example:Noisy and busy environment, users maybe talking while using the system
– Social : Sharing of files, displays, privacy, locking
– Organizational: Hierarchy, IT departments, user support,
communications structure, availability of training
– Users
● Novice : step-by-step, constrained, clear information
● Expert : flexibility, access, power
● Frequent: short cuts
● Casual/infrequent: clear instructions, menu paths
Example: Majority of users under 25,comfortable dealing
with technology.
● Usability
– Learnability, flexibility, throughput
Example: Simple for new users, memorable for frequent users, efficient,
deal easily with user errors
●IMPORTANT
– User requirements and usability requirements
refer to different things.
● Kinds of requirements
– What factors (enviornmental, user, usability) ?
● Selfservice cafeteria paying using credit system
● Nuclear plant control room
● Distributed car design team
Resource: http://www.id-book.com/
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