COMMENTARY


Requirements identify the essential ques- tions that testing must answer to verify that the system provides the desired capabilities. Te systems engineering “V” model demonstrates the importance of requirements and their relationship to testing. Te V model can also be described as a pyramid, with require- ments development and testing forming the base for delivering an effective system. (See Figure 1.) Requirements also estab- lish the level of statistical confidence and precision required for adequate verifica- tion of capabilities.


KNOWING YOUR ENVIRONMENT Te test and evaluation community has observed five common challenges to well- developed requirements. Tese enemies of sound requirements have stymied program development and increased the scope of testing. All acquisition stakeholders at all echelons must understand the risks these enemies carry with them and consider those risks while developing and staffing system requirements. Requirements devel- opment is a team effort, so requirements developers are encouraged to involve all stakeholders early in the process.


The following examples are actual requirements taken from recent Army requirements documents. Te intent is to foster a practical understanding of the risks in requirements development and their potential impacts. In many cases, these examples were revised as part of the document staffing process.


CHALLENGE #1: NOT OPERATIONALLY FOCUSED A best practice is to ask, “Do I still want this system if it can’t meet this require- ment?” Answering “yes” to this question probably means that the requirement is not linked to the operational need the system is intended to fill and should be revised or


FIGURE 1


Requirement design


System design


Architecture design


Modular design


Acceptance test


System test


Integration test


Unit test


Coding


THE ‘V’ MODEL OF SYSTEM DEVELOPMENT


The V model summarizes the stages of systems engineering. Requirements definition is key to all subsequent system development efforts, including testing. (Image by U.S. Army Acquisition Support Center (USAASC) and www.am7s.com)


deleted. As an example of a requirement that is not operationally focused, consider this key performance parameter (KPP) for an artillery round.


KPP: Artillery round is effective against moving targets.


It is certainly possible to fire artillery rounds against a moving target. However, this is not the primary purpose or mission


for artillery rounds; rather, it is something usually saved for extreme circumstances. Tis requirement increases the risk that the system fails the requirement in test- ing, potentially delaying system fielding. Te requirement also drives lengthy and expensive testing since there are many things, such as target type or range to target, that could affect whether the round is effective against moving targets.


https://asc.ar my.mil


147


Verification phases


Validation phases


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