EGNR 300

Customer Needs--------------------------

ENGR 300Dept. of Computer Science and Engineering

University of Bridgeport, CT 06601

Primary Goal

To develop a complete, correct and

consistent set of requirements for the projectThe Three C’s

Secondary Goal

To establish a comprehensive set of

constraints under which the requirements

are to be met.

Terminology

NeedsWantsRequirementsConstraintsSpecifications

Needs

the basic conditions and results necessary to solve a problem or achieve the customer’s goal

sometimes are subjective, qualitative and difficult to measure

Wants

things desired by the customer, but not necessary to solving the problem or achieving the goal

consider wants if: they have minimal impact on the project they are important to customer

assign wants lower priority than needs

Requirements

are the relevant needs and wants related to the problem or project

should focus on WHAT, not HOWshould not excessively limit the end

results or how they might be achievedform the basis for more detailed

SPECIFICATIONS to be formulated in the next phase of the design process

Constraints

limitations or restrictions beyond the basic needs and customer wants

may apply to the end product safety, reliability, environmental factors..

frequently relate to the process of achieving the end result budget, schedule, development

standards..

Specifications

are based on the established requirements and constraints

translate or interpret requirements in terms of specific, measurable parameters

are used as “yardstick” against which final product is measured

What is the source of project requirements?

External CustomerManagerCoworkerAnother DivisionSelf-initiative

Whomever initiates the project is the primary source of project requirements!

Customer Factors

The person responsible for requesting the project is the “customer”

Customers do not always know what they want

Customers do not always know what is technically feasible

Customers generally have only a “big picture” perspective of the end result

Desired Characteristics of Requirements

Completeness

The requirements must completely satisfy all the needs of the customer Needs are constantly changing Customers may not be aware of some of

their needs

Desired Characteristics of Requirements

Correctness

The requirements must satisfy the actual needs of the customer

Customers often think they want one thing, but really want another

Customers often have restricted views of how the problem should be solved

Desired Characteristics of Requirements

Consistency

No two requirements should conflict with one another

The speed limit on the road will be 55 MPH

Curves may have a radius up to 100 ft

Remember

Solve the right problem&

Solve the problem right!

Extract a complete, correct and consistent set of requirements

A Requirements Capture Approach

1. Extract an initial set of requirements2. Evaluate and refine initial requirements3. Prioritize requirements4. Evaluate the three C’s5. Identify constraints on the solution6. Document the requirementsRemember: Focus on what is to be

done. Don’t bog down in how to do it.

Step 1: Initial Requirements

Listen to the customerAsk questions - questions, questionsUse relevant prior experience to

help identify requirements customer’s experiences your company’s experiences

Step 2: Evaluate Initial Requirements

What is the apparent problem?What is the real problem?What are the needs?Distinguish between needs and

wantsIs “no action” an alternative?How will we measure success?

Step 3: Prioritize Requirements

Separate needs from wantsIdentify the single most important needRepeat with remaining listPrioritize wants in the same way

Sometimes wants are important enough to the customer that they

should be treated as needs

Step 4: Evaluate the Three Cs

Check for completenessCheck for correctnessCheck for consistency

Step 5: Identify Constraints

Cost - What is the project budget? The budget is fixed beforehand The budget is flexible and you have input

Schedule - When must the project be complete?

Quality - What are the quality requirements of the project?

Performance - speed, throughput, power consumption, etc.

Identify Constraints (cont’d)

Human - end user skills, training, “user friendliness”, etc.

Physical - size, weight, etc.Environmental - local/global impact,

reusability, disposal/salvage, etc.Safety - human, equipment, productReliability - What percentage of the

time is the result expected to operate?

Identify Constraints (cont’d)

Maintenance - Who will maintain?Modifiability - extend capabilities,

etc.Usage Environment - noise limits,

etc.Development Standards - internal

policies, documentation, EPA, OSHA, etc.

Step 6: Document Requirements

1. Brief statement of problem or project

2. List the requirements: Use outline format to simplify references Limit each entry to 3 sentences or less Incorporate constraints into requirements List requirements in order of priority

Requirements vs. SpecificationsRequirements

define what the customer wants may be subjective, qualitative, difficult to measure

Specifications define what will actually be delivered respond to:

customer’s needsyour organization’s capabilitiestechnology and resource availability

always measurable

Specifications.....

Precisely define the end product or result should quantify the customer’s needs and

specify the degree to which the needs will be met

should not limit how the customer’s needs are to be addressed

Consist of: a measurable quantity (a metric) and a value or range of values

Specification Forms

At least 400 units per minute processing rate...

No more than 2 defects per thousand...Between 180 °C and 186 °C...Nominal ± tolerance (183 ± 3 °C)Specific or exact (Sears #127 green)Discrete values (shall accept 1, 2, and

3 inch pipe)

Specifications as GoalsInitial specifications are based on:

customer’s needs previous experience what others can do what you would like to achieve

Initial specifications are used to evaluate alternate strategies for achieving the requirements

Specifications are subject to change, but only with the customer’s approval

Rules for Creating Specifications

1. Focus on the end RESULTS.2. Do not build your ideas of how to achieve

the results into the specifications.3. Make sure that each requirement is

covered.4. Make sure that the customer’s interests

are protected.5. Make sure that your interests are

protected.