name hometown program employer/student fun fact 1

•Name•Hometown•Program•Employer/Student•Fun Fact

1

IntroductionThe Requirements Problem (1)

Requirements Problem

•What is the goal of writing requirements▫Quality Software▫On time▫At or under budget▫Satisfied all of the users needs

And as many wants as possible

•Need to stay focused on the short and long term

Copyright Leffingwell, Widrig, & SIS Faculty


•Software development process ▫Is comprised of several activities ▫All of which must work together

•This will accomplish the objectives otherwise you have wasted effort


Requirements Problem•Developing software is like manufacturing

▫You have set times, locations, and people responsible for certain tasks

▫You should always provide a means for feedback and have error detection

•The most effect companies at manufacturing produce a product that best meets the consumers needs!!



•SW Development is a highly customized product … ▫Two models

Develop per customer Give enough options for all users

▫With obvious exceptions of shrink-wrapped COTS (Commercial Off-The-Shelf)

•Must find a way to effectively manufacture software that can be customized.


Requirements Problem• Efficient manufacturing of a product includes:

▫ Accurate specification of product▫ Efficient production process▫ Ability to quickly ID & remove defects

• Unlike most products, most SW defects can be repaired/fixed▫ Eliminates having to discard defective products▫ But can be very expensive to fix

Analysis Development QA …


Requirements Problem•What are some of the issues that we face

▫Who are all the users?▫Do the users know what they want?▫What is the users budget?

•This presents a difficult scenario in that you need to establish the first two pieces before you can make a decision on what you can do with their budget



•How do most projects fair▫Not good!!!!

Study done in the 90s reports that in the US $250 Billion/yr in application development $2.3 million for a large company project 31% of projects are cancelled @ cost of $81

billion 53% of projects cost double or more than the

original estimate



•Important questions the studies did not ask▫Did the completed software meet the users

needs? Was anything cut to get the software done

▫What was the quality of the product? QA tested? Known Issues

▫Is it maintainable? Feasibility of updates Availability Scalability w/ performance can be a big issue


Requirements Problem• So why do these projects fail?

• The most common factors are▫ 13% Lack of user input

We do voice of the customer Customer steering committees Alpha and Beta releases

Voice of the business What is a good direction from a business standpoint Input from cross functional teams

▫ Other business units▫ Other teams (QA, DEV)

▫ 12% Incomplete requirements and specs▫ 12% Changes in requirements and specs

• All directly related to managing requirements• All communication issues



•So how can we make a project successful

•Communication!!!▫Clear complete requirements▫Executive and management support

Some projects will run over budget or need more resources

▫User involvement


Requirements Problem•ESPITI (1995) Study of SW problems

▫See fig 1-1 p. 8 (next slide)

▫2 largest problems Requirement Specifications Managing Requirements

▫Coding is rarely the major problem It is usually the most expensive They code what is designed


Requirements Problem•Figure 1.1


Requirements Problem•Studies done by (3 boards suggest)

▫Keys to successful SW Development Ongoing communication with the users

During requirements elicitation Thorough documentation of requirements

User Validation of requirements Maintenance of reqs as they change Traceability of reqs throughout project to

ensure they’re implemented▫This requires a defined process that is

followed


Requirements Problem•How do software defects originate?

•Capers Jones study (1994) on SW Defects▫Reqs contribute most defects to delivered

SW▫Design defects come in a close second▫56% of defects due to the above 2 reasons▫Coding defects are common but also easier

to fix


Requirements Problem•Table 1-1 (Capers Jones Study)


Defect Origins Defect Potentials

Removal Efficiency

Delivered Defects

Requirements 1.00 77% 0.23

Design 1.25 85% 0.19

Coding 1.75 95% .09

Documentation 0.60 80% 0.12

Bad Fixes 0.40 70% 0.12

Total 5.00 85% 0.75


•Cost of fixing defects▫Studies that show the costs of fixing errors

Cost progressively increases as the SW process continues

100 – fold increase in cost to fix the error in the Maintenance phase versus the Reqs. Phase A requirement defect cascades into design

coding, etc


Requirements Problem•Figure 1-2



•Requirement defects can cause ▫Re-specification, redesign, recoding,

retesting, …▫Re-education of customers/users▫Lost sales/Recognition of revenue▫Refunding money ▫Product recalls▫ Emergency patches/Hot fixes▫Warranty Costs, Legal judgments



•So how are we doing now:▫Not much better

Still about 30% of projects fail http://www.ambysoft.com/surveys/success20

07.html http://www.umsl.edu/~sauterv/analysis/6840_

f03_papers/frese/▫This stresses the need for increased

training!

name hometown program employer/student fun fact 1

Documents

budget copyright leffingwell

effortcopyright leffingwell

long termcopyright leffingwell

users budget

customized product

users needsand

incomplete requirements

completed software