Case Study of a Problem in Software Engineering

8/18/2019 Case Study of a Problem in Software Engineering

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Lecture 1 , 2Problem Defnition


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Problem Pre- Requisite

• First prerequisite you need to ull fll beore bconstruction is a clear statement o the probthe system is supposed to sole! "his is socalled #product ision,$ #mission statemen#product defnition!$ %ere it&s called #

defnition!$


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'ddressing Problem!

• %o( to address the problem)• *tep 1) +ain agreement on the problem defnition

• *tep 2) nderstand the root causes

• *tep ) .dentiy the sta/eholders and the users

• *tep 0) Defne the solution system boundary!

• *tep ) .dentiy constraints to be imposed on the solu


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Step 1: +ain 'greement on the Problem Defnition

• "o gain agreement)rite Do(n the Problem Defnition 3 does

eeryone agree4

* l bl


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*ample Problem)+oods'res• #5 a mail-order catalog company 5

manuactures 6 sells a ariety o

ine7pensie, miscellaneous items or homand personal use!$

Problem) insu8cient proftability

• "he problem behind the problem4


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*tep 2) nderstanding the Root 9auses

• Root Cause Analysis• basic and contributing causes are discovered in a

process similar to diagnosis of disease.

• The goal is to find out:• what happened

• why did it happen

• what do you do to prevent it from happening aga

d t di th R t


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nderstanding the Root9auses• ;s a simple matter o as/ing the people

directly inoled

• . the problem is more serious, it may be necessary toperorm a detailed inestigation o each contributingproblem and to quantiy its indiidual impact

• ?y simple brainstorming by participants (ho hae/no(ledge o the problem

• or more rigorous e7periment

• *o, (hen the causes are determined, a question)are all the causes (orth f7ing4

• cost o the f7 e7ceeds the cost o the problem4

•(hich ones to f74


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nderstanding the Root 9auses Acont!B

Example

• Problem:“Last summer, we noticed that

several trees appeared to bedying”

• Cause:

• decorative plant beds weresuffocating the tree roots

• Solution:• remove plant beds

• Grass is the best choice toplace around a tree


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A Classical Example:

a pool of oil on the factory oor

• Day 1:

• clean it up

• Day 2: e7actly the same pool o oil in the sameplace

• follows a predictable scenario of blame and resentment

• Day 3: more oil !

• And so on …

Plantanage

oil


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A pool of oil on the factory oor -

Root Cause Analysis approac:

• Day 1:• why the oil (as there at all !

• Cause 1: a leaking gasket in the pipe above

• Cause 1.1: supplier>s gas/ets had a bad record o lea/age buthat they had been selected as a supplier o choice because o

the lo( price • why economy (as used as the deciding criterio

or selection o equipment!

• Cause 1.1.1: the directie rom the Product anager had beto be e7tremely cost conscious#

!oral: the Plant Manager was responsible for the oil p

oil

Plantanag


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+oods'res) Problem behind the Problem4!!!

Problem) insucient protability• "otal Huality anagement A"HB techniqu

IJ• 9ause 1) the problem is due to the high cost

of nonconformance ! cost o all the things that go (roand produce (aste, scrap, and other e7cess costs

• 9ause 1!1) Largest contributor is "#cess Scrap

• "he problem behind the problem in scrap4


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• $%M $echni&ue: Fishbone Diagram•

's/ the peopleK• +oods'res) sources contributing to the

too much

scrap 4!!!

're all#bones$contributingequally to thee7cess scrap4


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'ddressing $'" Root 9ause

• (etermine the contribution of eachcause

• $echni&ue: Pareto 9hart

• +oods'res) Huality data demonstrates thatmany root causes are simply not (orth f7ing

"he e7istingsalesorder system isapoor legacy

code

Case Study of a Problem in Software Engineering

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