software quality measurement and metrics (1)

8/20/2019 Software Quality Measurement and Metrics (1)

1/37


2/37

Software QualityMeasurement and Metrics 2

Outline￭ Basic Terminologies

￭ Project Indicators

￭ Classication of Software Metrics

￭ Software Quality Metrics

￭

Software Maintenance Metrics￭ Software Defects Classication


3/37

Software QualityMeasurement and Metrics

Software Metrics

!Software Metrics let you "now w#ento laug# and w#en to cry$

%Tom &li'(


4/37

Software QualityMeasurement and Metrics )

Basic Terminologies￭ Measure * a +uantitati,e indication of some

attri'ute of a -roduct or -rocess. /or e0am-le1

errors1 3244 5OC etc￭ Measurement * t#e act of determining a

measure.

￭ Metric * a +uantitati,e measure of t#edegree to w#ic# a -roduct or -rocess-ossesses a gi,en attri'ute. /or e0am-le1 defects 6 75OC. Metric is1 'asically1 a ratio oftwo related measures.


5/37


6/37

Software QualityMeasurement and Metrics =

Ty-es of Measurements￭ Direct Measures

￭


7/37

Software QualityMeasurement and Metrics @

Indicators￭ Indicator * is a metric or com'ination of

metrics t#at -ro,ide insig#t into t#e software

-rocess1 -roduct or -roject. /or e0am-le1 twoteams using two di>erent re,iew a--roac#esgi,e an indicator of t#e 'etter a--roac#.

￭ Indicators are of two ty-es:￭ Process Indicators￭ Project Indicators


8/37

Software QualityMeasurement and Metrics A

Indicators￭ Process Indicators

￭ sed to gain t#e insig#t into t#e ecacy of t#ee0isting -rocess.

￭ T#ese are collected across all -rojects and o,er a long-eriods of time.

￭ /or e0am-le1 PSP and TSP etc.￭ Project Indicators

￭ sed to asses t#e status of t#e -roject.￭ Trac" -otential ris"s.￭ nco,er -ro'lems areas 'efore t#ey occur.￭ djust t#e wor" Eow and tas"s accordingly.￭


9/37

Software QualityMeasurement and Metrics H

Classication of Metrics


10/37


Quality Metrics￭ Pro,ide indicators to im-ro,e t#e

+uality of t#e -roduct.

￭ T#ere are many +uality attri'utessuc# as maintaina'ility1 usa'ility1integrity and correctness etc.

%see McCallFs Quality Model(


11/37


,aila'ility￭ ,aila'ility is concerned wit# system failure

and its associated conse+uences.￭ T#e a,aila'ility of a system is t#e -ro'a'ility

t#at it will 'e o-erational w#en it is needed. T#is is ty-ically dened as:

￭ /rom t#is come terms li"e HH.H a,aila'ility1or a 4.3 -ro'a'ility t#at t#e system will not

'e o-erational w#en needed.

Mean Time to Failure

Mean Time to Failure + Mean Time to

Repair

α


12/37


Maintaina'ility￭ Maintaina'ility is t#e degree of easiness

wit# w#ic# a -rogram can 'e correctedif an error is encountered or c#anged if

user re+uirement c#anged.￭ Mean Time To Change (MTTC) is t#e

indirect measure to measure t#emaintaina'ility.

￭

MTTC is t#e mean time to fulll ac#ange re+uest.￭ 5ower MTTC means #ig# maintaina'ility.


13/37


Correctness￭ Correctness is t#e degree to

w#ic# t#e software -erforms its

re+uired function.￭ common way to measure t#e

correctness is Defect Density

%DD( No. of Defects reported by theuser

Size of the program in K!"

DD


14/37

Software QualityMeasurement and Metrics 3)

sa'ility￭ sa'ility is concerned wit# #ow easy it

is for t#e user to accom-lis# a desired

tas" and t#e "ind of user su--ort t#esystem -ro,ides.￭ It 'e 'ro"en down into:

3. 5earning system features

2. sing a system eciently. Minimi;ing t#e im-act of errors

). da-ting t#e system to user needs

. Increasing condence and satisfaction


15/37


Integrity￭ 'ility of t#e system to wit#stand

attac"s on its security.￭

Integrity is measured in terms ofthreat and security .￭ T#reat * -ro'a'ility t#at an attac" of s-ecic ty-e

will occur wit#in a gi,en time.

￭ Security * -ro'a'ility t#at an attac" of s-ecic

ty-e will 'e re-elled.

.Integrity = ∑ [ 1 - (threat) * (1 – security) ]


16/37


17/37


18/37

Defect Kate

Defect Injection Kate %DIK(

L%?o of in -rocess defects( %?o of CustomerNre-orted

defects(

ctual si;e of t#e -roduct


19/37

Defect found 'y remo,al o-eration

Defect Present at remo,al o-eration

System Testing

cce-tance Testing

8arranty su--ort Customer re-orted during wor" -roduct re,iews

Tec#nical Ke,iews

Defect Kemo,al


20/37


21/37


22/37


23/37

P#ase 'ased Defect ecti,eness

ig# 5e,el Design Ins-ectionecti,eness

Defects Kemo,ed

Defects e0isting %


24/37

Phases Defect Injected DefectRemov

ed

DefectRemaine

d in

eachPhase

In-Process CustomerReporte

d

Requirements *+ + ** -

High leveldesign

++ ./ 01 -2

Low LevelDesign

-. - .2 +

Code // 2 /2 /

Unit Testing 3* +- 22 .2

System

testing

03 -. /2 +2


25/37

Calculate Defect Density if si;e is 444 75OC

Defect Kate Defect Kemo,al


26/37

Software MaintenanceMetrics


27/37

Some Maintenance Metrics

/i0 'ac"log and 'ac"log managementinde0

/i0 res-onse time and 0res-onsi,eness

Percent delin+uent 0es

/i0 +uality


28/37

/i0 'ac"log and 'ac"logmanagement inde0

BMI?um'ers of -ro'lem closed during t#e mont#

?um'ers of -ro'lems arri,als during t#e mont#

s a ratio if BMI is larger t#an 3441 it meanst#e 'ac"log is reduced1 if is less t#an 344t#an it is increased

344


29/37


30/37

Percent delin+uent 0es

?um'er of 0es t#at e0ceeded t#e

res-onse time criteria 'y se,erityle,el

?um'er of 0es deli,ered in a

s-ecied time

T#is metric is only for closed -ro'lems

344


31/37

Some ot#er measures

$ciency8#ere

Si;e J 75OC

ort J man year

Time J ours

B J constant or ascaling factor and is afunction of t#e -rojectsi;e.


32/37

K


33/37

Defects Classication

Software Quality Assurance


34/37

Software Quality

Measurement and Metrics )


3.


35/37

Software Quality

Measurement and Metrics


. Bugs 6 /ault￭ It is a -rogram defect t#at is encountered in o-eration

%al-#a testing1 'eta testing or software o-eration(￭

ll defects do not cause 'ugs.￭ /or e0am-le1 27

). /ailure￭ failure is a malfunction of userFs installation.￭ It may result from a

￭ Bug￭ Incorrect installation￭ Communication line #it￭ ardware failure etc.


36/37

Software Quality

Measurement and Metrics =


. Pro'lems￭ Pro'lems are user encountered

diculties.￭ Pro'lems are #uman e,ents w#ereas

/ailures are system e,ents.

￭ -ro'lem may result from:￭ /ailure

￭ Misuse

￭ misunderstandings


37/37

/eel free to as"

T#an"s

Software Quality Assurance

software quality measurement and metrics (1)

Documents