Work can often be divided up so that the smaller pieces are valuable on their own. By dividing work this way, a team can deliver value incrementally. The team can choose a short period of time called an iteration and select a small amount of work to complete in that time. This work should be valuable on its own. For example, if a team is building something, then at the end of each iteration whatever is built is usable as it is. This means that each iteration includes all the planning and design as well as construction or creation necessary to deliver a final product or result.
For example, a volunteer group may desire to attract new members. A non-agile approach would have the group plan their membership campaign completely before actually executing on it. An agile approach using iterative delivery would have the group plan a small piece of work that will attract some small number of new members, execute it, and then start a new iteration. One iteration may cover the creation of and delivery of a door-to-door flyer in a neighborhood. Another iteration may cover the design, creation and publishing of a small advertisement in a local newspaper. Each iteration includes all the steps necessary to produce a furthering of the group’s goal of attracting new members.
In a business environment, iterative delivery allows for a much faster return on investment. The following diagram compares delivering value iteratively with a non-agile project delivery where results are delivered only at the end of the project:
One can see clearly from the diagrams that the non-agile delivery of value at the end of a project is also extremely risk prone and suseptible to change. If the project is cancelled just before it delivers, then a fairly substantial amount of effort is wasted. In the agile iterative delivery situation, an endeavor can be cancelled at almost any time and it is likely that substantial value has already been delivered.
Even if the work cannot actually be delivered incrementally, it almost always can be divided in a way so that it can be inspected in stages. Either method of dividing work allows us to do the work in iterations.
Iterations are fixed and consistent units of time during which work is performed and between which planning, inspection and adjustment is done. The empowered team will decide on the length of iterations for their work. As a rule of thumb iterations should be shorter than the horizon of predictability. Generally, iterations should never be longer than one month, no matter what the endeavor.
At the end of each iteration, a demonstration of the work completed is given to the stakeholders in order to amplify learning and feedback. Between iterations, the stakeholders collaborate with the team to prioritize the remaining work and choose what will be worked on during the next iteration. During the iteration, the stakeholders need to be accessible for questions and clarifications.
Iterative and incremental delivery is used to allow for the early discovery and correction of mistakes and the incorporation of learning and feedback while at the same time delivering value early.