Scrum is based on the theory of empirical process control, which relies on transparency, inspection, & adaptation. Scrum is also both iterative and incremental.
Scrum Rests on Three Pillars of Empirical Process Control
To make decisions, people need visibility into the process and the current state of the product. To ensure everyone understands what they are seeing, participants in an empirical process must share one language.
Scrum Reviews Provide Transparency.
Scrum’s frequent reviews give team members and stakeholders a clear view into the state of the project.
To prevent deviation from the desired process or end product, people need to inspect what is being created, and how, at regular intervals. Inspection should occur at the point of work but should not get in the way of that work.
Scrum Reviews & Retrospectives Offer Inspection Opportunities.
Scrum teams inspect their completed work and their process at the end of every iteration during the sprint reviews and sprint retrospectives.
When deviations occur, the process or product should be adjusted as soon as possible.
Scrum Teams Can Adapt the Product at the End of Every Sprint.
Scrum allows for adjustments at the end of every iteration.
Scrum Is Iterative & Incremental
A process for arriving at a decision or a desired result by repeating rounds of analysis or a cycle of operations. The objective is to bring the desired decision or result closer to discovery with each repetition (iteration).1
Scrum’s use of a repeating cycle of iterations is iterative.
A series of small improvements to an existing product or product line that usually helps maintain or improve its competitive position over time. Incremental innovation is regularly used within the high technology business by companies that need to continue to improve their products to include new features increasingly desired by consumers.1
The way Scrum teams deliver pieces of functionality into small batches is incremental.
1 Source: BusinessDictionary.com