Requirement Enginering Software Requirement Tutorial 14

7/29/2019 Requirement Enginering Software Requirement Tutorial 14

1/22

1

Requirements Errors

Lecture # 14


2/22

2

Todays Topics

Requirements errors

Addressing requirements errors


3/22

3

Requirements Errors


4/22

4

Requirements Error/Defect

A deficiency in the requirements

quality that can hamper software

development


5/22

5

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


6/22

6

Requirements Errors - 2

It is difficult to detect requirements

errors once they flow downstream

Requirements errors are most

expensive to eliminate


7/22

7

Software Development Process

software

requirements

preliminary

design

detaileddesign

coding

unittesting

integration

testing

system

testing

delivery

production

deployment

maintenance

and

enhancement

software

system test

planning

integration

test

planning

unit testplanning

1

2

3

4

5

6

7 8

9

10

11

12

MIL-STD-2167A


8/22

8

Types of Requirements Errors

Errors of omission

Errors of commission

Errors of clarity and ambiguity

Errors of speed and capacity


9/22

9

Errors of Omission

Errors of omission are most common

among requirements errors

Domain experts easily forget to convey

domain knowledge to requirements

engineers, because they consider thatto be obvious and implicit


10/22

10

Errors of Clarity and Ambiguity

Second most common errors are thoseof clarity and ambiguity

Primarily, because natural languages(like English) are used to staterequirements, while such languages are

themselves ambiguous For example: object


11/22

11

Errors of Commission

Errors of commission can also find

their way into the requirements

documents


12/22

12

Performance Errors

Performance, that is errors of speed

and capacity, are also found in

requirements

Primarily, these occur due to

conflicting understanding or competingneeds of different stakeholders


13/22

13

Negative Impact of Requirements

Errors - 1 The resulting software may not satisfy

users real needs

Multiple interpretations of

requirements may cause disagreements

between customers and developers,wasting time and money, and perhaps

resulting in lawsuits


14/22

14

Negative Impact of Requirements

Errors - 2 Negative impact on humans

Unsatisfied customers and developers

Lack of interest in automation of

processes

Blame game


15/22

15

Addressing Requirements Errors

Prevention

Removal


16/22

16

Prevention vs. Removal

For requirements errors, prevention isusually more effective than removal

Joint application development (JAD),quality function deployment (QFD), andprototyping are more effective in defectprevention

Requirements inspections and prototypingplay an important role in defect removal


17/22

17

Defect Prevention - 1

Dont let defects/errors become part ofthe requirements document or

requirements model in the first place How is it possible?

Understanding application domain and

business area is the first step in defectprevention


18/22

18


Training in different requirements

engineering activities (elicitation, analysis

and negotiation, specification, andvalidation) is also very important for defect

prevention

Allocating enough time to conductrequirements engineering activities also is

very important in this regard


19/22

19


Willing and active participation of

stakeholders in different activities of

requirements engineering. That is why

JAD is very useful in defect prevention

as far as requirements errors are

concerned


20/22

20


An overall commitment to quality and

emphasis on using documented

processes is also a very important

An overall commitment to process

improvement


21/22

21

Summary

Introduced the concept of requirements

errors and types of requirements errors

Discussed the impact of requirements

errors

Discussed error prevention inrequirements


22/22

22

References

Requirements Engineering: Processes

and Techniques by G. Kotonya and I.

Sommerville, John Wiley & Sons,

1998

Software Quality: Analysis andGuidelines for Success by Capers

Jones

Requirement Enginering Software Requirement Tutorial 14

Documents

Transcript of Requirement Enginering Software Requirement Tutorial 14