Requirements Errors 1-Software Requirement-Lecture Slides, Slides of Software Project Management

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Requirements Errors

Lecture # 14

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Today’s Topics

• Requirements errors• Addressing requirements errors

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Requirements Error/Defect

• A deficiency in the requirements

quality that can hamper softwaredevelopment

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Requirements Errors - 1

• Errors and omissions find their way in

different requirements documents

• If not removed, requirements errors

usually flow downstream into design,code, and user manuals

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Software Development Process

softwarerequirements

preliminarydesign

detaileddesign

coding

unittesting

integrationtesting

systemtesting

deliveryproductiondeployment maintenanceand enhancement

softwaresystem testplanning integration

testplanning unit testplanning

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(^101112)

MIL-STD-2167A

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Types of Requirements Errors

• Errors of omission• Errors of commission• Errors of clarity and ambiguity• Errors of speed and capacity

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Errors of Clarity and Ambiguity

• Second most common errors are those

of clarity and ambiguity

• Primarily, because natural languages

(like English) are used to staterequirements, while such languages arethemselves ambiguous

• For example: object

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Errors of Commission

• Errors of commission can also find

their way into the requirementsdocuments

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Negative Impact of Requirements

Errors - 1

• The resulting software may not satisfy

user’s real needs

• Multiple interpretations of

requirements may cause disagreementsbetween customers and developers,wasting time and money, and perhapsresulting in lawsuits

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Negative Impact of Requirements

Errors - 2

• Negative impact on humans
  • Unsatisfied customers and developers– Lack of interest in automation of

processes

• Blame game

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Prevention vs. Removal

• For requirements errors, prevention is

usually more effective than removal

• Joint application development (JAD),

quality function deployment (QFD), andprototyping are more effective in defectprevention

• Requirements inspections and prototyping

play an important role in defect removal

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Defect Prevention - 1

• Don’t let defects/errors become part of

the requirements document orrequirements model in the first place

• How is it possible?• Understanding application domain and

business area is the first step in defectprevention

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Defect Prevention - 3

• Willing and active participation of

stakeholders in different activities ofrequirements engineering. That is whyJAD is very useful in defect preventionas far as requirements errors areconcerned

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Defect Prevention - 4

• An overall commitment to quality and

emphasis on using documentedprocesses is also a very important

• An overall commitment to process

improvement