Agile, Waterfall, or Hybrid: An IF4IT Framework for Choosing Delivery Methodology - Glossary of Terms and Phrases
Agile, Waterfall, or Hybrid: An IF4IT Framework for Choosing Delivery Methodology
Chapter 2. Glossary of Terms and Phrases
The following terms are used throughout this document with specific meanings.
| Term | Definition |
|---|---|
| Agile | A delivery methodology in which work is delivered as a continuous stream of small, independent, individually valuable units — commonly expressed as User Stories grouped into Enablers and Epics — delivered in consistent, committed cycles. Agile tolerates the possibility of a delivered increment failing in use, because the consequence of such failure is low and the correction loop is fast. |
| Waterfall | A delivery methodology in which work is delivered as a bounded, integrated effort that advances through a sequence of stages, with formal verification at each stage before the work proceeds. Waterfall concentrates the detection of failure into pre-delivery stages so that failure is found and corrected before the Product or Service is released. |
| Hybrid | An outcome in which a Product or Service is delivered predominantly through an Agile stream, while one or more bounded, integrated components are isolated and delivered through Waterfall, reintegrating with the Agile work at defined points. A Hybrid must be earned by demonstrating that the Waterfall components can be cleanly isolated; it is not a default or a compromise of convenience. |
| Product or Service | A defined thing with an identity and a lifespan, expected to receive intentional improvements over that lifespan. The Product or Service is the entity to which this framework is applied. The term Service is understood broadly: it covers ongoing operational services and also bounded undertakings performed to deliver a defined outcome. Examples include a software application, an integrated circuit, an aircraft, a delivered business service such as claims processing, and a merger, acquisition, or divestiture. |
| Delivery Methodology | The disciplined approach by which work to create or improve a Product or Service is organized and delivered. This framework concerns three: Agile, Waterfall, and Hybrid. |
| Unit of Work | A discrete portion of the work required to create or improve a Product or Service. The framework assesses whether work can be partitioned into small units and whether those units can be delivered as valuable increments. |
| Increment | A unit of work once delivered. An increment is incrementally valuable when it provides standalone value upon delivery, independent of the units delivered before or after it. |
| Decomposability | The degree to which a body of work can be partitioned into small units. The first structural indicator of the framework. |
| Incremental Deliverability | The degree to which the small units of a body of work can be delivered progressively, each delivered increment having standalone value. The second structural indicator. Distinct from Decomposability: work may be decomposable yet not incrementally deliverable. |
| Time of Delivery | Whether the increments of a body of work can be delivered in consistent, committed cycles. The third structural indicator. The test is the ability to commit to a consistent cycle, not the absolute duration of the cycle. |
| Delivery Cycle | A consistent, committed period within which an increment is delivered. Most commonly one to four weeks in length, though the specific duration is defined by the Product or Service Owner. The defining property of a delivery cycle is consistency and commitment, not its length. |
| Consequence of Failure | The severity of harm that results if a delivered increment fails in use. The framework’s gating indicator. Severe consequence — harm to humans, material brand damage, regulatory or legal breach, irreversible loss — directs work to Waterfall regardless of the structural indicators. |
| Fail Fast | The principle of detecting and correcting failure as early and as cheaply as possible. Both Agile and Waterfall pursue this principle; they differ in where, relative to delivery, they locate the point at which failure is detected. |
| Decision Gate | A point in the framework at which one indicator can determine the outcome on its own, overriding the others. Consequence of Failure is the framework’s decision gate. |
| Uniformity Check | The step at which a practitioner determines whether a Product or Service is uniform in character or contains work of a materially different character. Applied to work that has been assessed as Agile-shaped, to determine whether a Hybrid outcome should be considered. |
| Exception Scan | The step at which a practitioner identifies the minority of units within a non-uniform Product or Service that differ in character from the whole. The Exception Scan does not enumerate and classify every unit; it identifies only the recognized exceptions. |
| Isolability Test | The test that determines whether the exception units identified by an Exception Scan can be separated from the main body of work — behind clean interfaces, on separable workstreams, with defined integration points — so that they run their own delivery cadence without forcing that cadence onto the rest of the work. A Hybrid requires the Isolability Test to pass. |
| Delivery Cost | The cost to deliver a Product or Service according to its methodology fit. Delivery cost is a property of the work; the tolerance for that cost is a property of the enterprise. Cost is an advisory consideration applied after the methodology fit has been determined; it never rewrites the fit. |
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