Requirements Prioritization Strategies | 3
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(necessary and urgent). For categorical scales, a definition of each categorical value needs to be
established so that all stakeholders prioritize from the same perspective. The table below summarizes
the priority value semantics.
Priority Semantics
High/Critical A critical requirement without which the product is not acceptable to the
stakeholder
Medium/Important A necessary but deferrable requirement that makes the product less
usable but still functional
Low/Desirable A nice feature to have if there are resources, but the product functions
well without it
Figure 2: Requirements Prioritization Semantics
Strategy: Subjective Ranking
Subjective ranking is a scheduling strategy in which each stakeholder assigns a priority value from a
scale. This strategy can often lead to conflicting priorities as all stakeholders' priority definitions have
the same weight.
Subjective ranking can be done through meetings or through an asynchronous medium such as email.
Each stakeholder provides his or her subjective opinion as to the importance of each requirement
using an agreed upon ranking scale. Ranking is done for all requirement types starting with the higher-
level requirements and then working down to the lower-level requirements; so, start with the business
requirements first, then go to the user requirements, and then finish up with detailed functional
requirements, non-functional requirements, and finally constraints. Finally, average the priority
estimates from all of the stakeholders to arrive at a consensus rank for the requirement.
For example, the functional requirement "mark all back-ordered items in bold" is not urgent, as it
does not address some immediate need of the business and may be deferrable, as there is not some
immutable deadline or regulatory mandate; so, it should be ranked as "low" or "desirable."
Group Estimation Techniques
Estimates for priorities (as well as other estimates such as time, effort, or risk estimates) can be
improved through the use of planning sessions where estimates are elicited from all stakeholders
using group estimation techniques. Among the most commonly used group estimation techniques are
Planning Poker and Delphi.
The Delphi technique is widely used for estimating time, effort, risk, and priorities. Estimates are initially
provided anonymously by a group of experts. Next, the team of experts discusses the estimates and
the providers of the highest and lowest estimates have to "defend" their findings. There must be
a reason that they are outliers: do they know something that the others don't know. Information is
exchanged in an open forum. Finally, a second set of estimates is provided anonymously. The final
estimates are then averaged. It is important that the estimation be done individually and anonymously
so that the estimates are not biased.
