System Requirements Flashcards
____ Capture the understanding of what is to be done (plural)
Requirements
Poor ____ are the single biggest problem for projects
Requirements
Requirements define:
- ‘What’ is to be done
- ‘How well’ it is to be done
- Under ‘what conditions’
Requirements drive ______
everything
True or False: a requirement may be a contractually binding statements
True
True or False: a requirement can not be documentation of a problem space
False
True or False: A requirement can not be a method by which a team communicates
False
NASA Requirement Conventions:
Requirements are binding - SHALL
Facts or declaration - WILL
Goals/Non-Mandatory - SHOULD
NASA Requirement Don’ts:
DO NOT USE:
must, have to, ought to, etc
Types of Requirements: (list them)
- Functional
- Performance
- Constraints
- Verifications
Define Requirement Type: Functional
Requirement which defines WHAT an item must do.
Define Requirement Type: Performance
Requirements which define and quantify HOW WELL an item must accomplish a task.
Define Requirement Type: Constraint
Requirements that capture operational, environmental, safety, or regulatory constraints (WHAT CONDITIONS)
Define Requirement Type: Verification
Requirements that capture how confidence will be established about the system performance in its intended environment.
Other types of requirements:
Stakeholder needs System Reqs Imposed Reqs (env.) Interface Reqs Regulation Reqs Implementation Reqs (we can't ride flying carpets to the moon) Verification Reqs
Cost incurred _____ ______ over the system maturity period. (Increase/Decrease, Sharply, Gradually)
Increases Gradually
System-Specific Knowledge _____ ______ over the system maturity period. (Increase/Decrease, Sharply, Gradually)
Increases Gradually
Commitment to Technology Configuration, Performance, and Cost _____ ______ over the system maturity period. (Increase/Decrease, Sharply, Gradually)
Increases Sharply
Ease of change _____ ______ over the system maturity period. (Increase/Decrease, Sharply, Gradually)
Decreases Sharply
Design Disciplines _____ ______ over the system maturity period. (Increase/Decrease, Sharply, Gradually)
Increase Gradually
Systems Engineering _____ ______ over the system maturity period. (Increase/Decrease, Sharply, Gradually)
Decreases Gradually
True or False: requirements will not change due to understanding of difficulties.
False
True or False: reqs change when priorities change.
True
Name some places where requirements are derived:
Stakeholder disclosures Goals/Objectives Constraints/Assumptions ConOPs FOMs PBS WBS
System boundaries are _______ ______-
External interfaces
List the methods for decomposing requirements:
- Flow-down
- Allocation
- Derivation
Define Requirement Decomposition Method: Flow-Down
Direct transfer from subsystem capabilities.
Example: power supply req of sat. system may be entirely flowed down to req of satellite’s solar power subsystem.
Define Requirement Decomposition Method: Allocation
Quantitative apportionment of resources from higher to lower levels using the same unit of measure.
Example: 1000 kg spacecraft may allocate 200 kg, 500 kg, and 300 kg to its three respective subsystems.
Define Requirement Decomposition Method: Derivation
Apportionment that is implementation specific.
Examples:
1. Launch vehicle propulsion will determine maximum payload mass.
2. Structural stiffness requirement (young’s mod) may be determined from natural frequency of launch vehicle.
Once requirements are decomposed for all levels of the system, ____ is established to connect them.
Traceablility
____ is used to analyse the impact of requirement/mission changes.
Traceability
If the parent requirements are incomplete, incorrect, ambiguous, conflicting, or unverifiable, the children requirements will be ______ _______.
Progressively worse
Define IDD:
Interface Definition Document: defines interfaces to existing systems
Define IRD:
Interface Requirement Document: defines interfaces for two developing systems.
What is an ICD?
Interface Control Document: Identifies the design solution for the physical interface (mechanical solutions & drawings)
When a system is decomposed into smaller segments, _____ are created.
Interfaces
Define a TBD Requirement:
To be decided req
Define a TBR Requirement:
To be resolved req
Good requirements are _ _ _ _ _
SMART
SMART
S - Specific M - Measurable A - Achievable R - Relevant T - Traceable
Name three mandatory characteristics of good requirements:
- Needed
- Verifiable
- Attainable
True or False: requirements can address more than one thing.
False
True or False: a specific requirement should only be understood in one particular way.
True
State a good requirement format: (three words)
WHO SHALL WHAT
These words are ________: flexible, lightweight, maximize, adequate, small, portable, easily
Unverifiable
These words are ________: as appropriate, so on, but not limited to
Ambiguous
True or False: A requirement addresses HOW to provide something.
False
Why ask if a requirement is necessary?
To determine if we even need it.
True or false, this is a good requirement: the lunar lander shall include an airlock.
False:
The lunar lander shall provide the capability to egress/ingress while maintaining pressure.
True or false, this is a good requirement: The spacecraft shall have a lifetime of al least five years.
True
True or false, this is a good requirement: The vehicle shall be safe in a minor crash.
False:
The vehicle shall meet all the safety requirements specified in the Safety Codes…
True or false, this is a good requirement: The vehicle shall allow extra-vehicular activities during operations phase.
True
Checklist for Requirements:
- Unambiguous?
- Free of unverifiable shit?
- Not implementation specific?
- Necessary?
- Free of operation description?
- Free of TBDs?
True or False: A requirement can contain an operation description.
False
Ask: ‘Does the developer have control over this?’
‘is this a need the product must satisfy or an activity involving the product?’
____ captures the motivation and assumptions of a requirement.
Rationale
Rationale or Requirement?
The UAV Shall be able to hover
Requirement
Rationale or Requirement?
over 99% of all US highway overpasses have a 14 foot clearance.
Rationale
The ______, is the set of techniques preliminarily proposed to test system requirements.
Requirement Verification Plan
True or False: When there are many operational scenarios, it is a good idea to choose the worst case scenario for your requirement verification plan.
True:
See DRM (ConOps and Scoping)
Design Reference Mission
What three things does requirement VALIDATION address?
- If we have the correct problem definition
- Do our requirement accurately capture this problem
- Are our requirements SMART or stupid?
Define SRR:
System Requirements Review
True or False: Requirement validation takes place after the SRR (System Requirements Review)
False, it takes place before the SRR
______ ______ is a process of ensuring that: the set of requirements is correct complete and consistent.
Requirement Validation
True or False: The cost of reconciling undefined/corrupted requirements stays more or less constant as the project matures.
False. The cost increases dramatically.