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Innovation and product development projects have environments characterized by many unknowns and rapid change. Recently, an emerging set of practices termed ''agile product development'' has caused traditional orthodox product developers and project managers to rethink their approach to creating fast and flexible projects <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>. As stated in ''The PDMA ToolBook 3 for New Product Development'', flexibility is one of the most important corner stones whenever considered the project planning. 
Moreover, in new-product development, most management approaches presume a high ratio of knowns to unknowns , and most planning defines prescribed pathways through developmental stages and decision gates <ref name= Innovation> Mark P. Rice, Gina Colarelli O'Connor, Ronald Pierantozzi,''"Implememnting a Learning Plan to Counter Project Uncertainty "''], MIT Sloan Management review, Winter 2008</ref>. At the same time, project environments reflect a very low amount of information at the beginning of the project, when the decisions importance is more relevant, while it increases as the project lifecycle is developed. 

To counter with this paradox, the Rolling-Wave technique is one of the newer agile tools that has been widely adopted as it yields benefits of improved speed, flexibility and customer value. Rolling wave is a robust, sophisticated way to manage the risks of innovation, to adapt to change, to align the organization, and to align the team towards breakthrough reults <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>. Recognizing that not all the aspects of a project can be fully defined or known at the starting stage, the Rolling-Wave planning allows the progressive elaboration of all the details as far as the project go on. The project management profession has used the term ''rolling wave'' referring to the expression "plan a little, do a little" to characterize its use of iteration along the project lifecycle<ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>.

The aim of this article is to contribute to the profession of project, program and portfolio management in:
#Understanding the purpose, importance and principles of The Rolling-Wave technique. 
#Identifying its key characteristics and major aspects.
#Recognizing its boundaries and limitations. 


''Developed by Gianluca Santinon''<br />
== Overview of the Rolling-Wave technique ==
[[File:Traditional VS Rolling Wave planning Approach.png | thumb | right | 500px | Traditional VS Rolling-Wave planning approach]]
Projects environments nowadays are evolving rapidly and business systems have become increasingly complex in order to optimize cost, quality, timeliness of results and comply with variations in regulations in marketplace <ref name ="Agility"> Larman, Craig, ''"Building the Agile Enterprise"'', 2004</ref>. Most innovation and product development success stories show that reduced organic teams of competent and motivate people, small batch sizes of information, iteration, and rapid feedback from the customer or user are the key principles to succeed <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>.
In a context described by the former quotes, the agile approach has become more and more popular, underlining the key of success for each project. As mentioned in the ''The PDMA ToolBook 3 for New Product Development'', an agile enterprise rapidly adapts to changing business challenges and opportunities. Agility has always been important for an enterprise to achieve and maintain competitive advantage. 
Agile organizations have the capability to quickly anticipate change as well as react to the unexpected. With this agile capability, these organizations are able to create value and do it with speed and flexibility <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>.

In these situations where the conditions are intricated and not easily predicted, the Rolling Wave has revealed to be one of the agile techniques that offers clear benefits and permits to overcome the brittle schedule problem towards an alternative robust planning. Defining a brittle schedule as a project that breaks easily due to a change in assumptions, the alternative robust planning can be seen as a project model that can withstand the stresses of change in the project, adapt to changes and serve to focus the project success. A robust plan is a useful tool for the project team to align and integrate its efforts in order to achieve a project characterized by speed, flexibility, and customer value added <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>.

With the term ''Rolling-Wave'' it is intended an iterative approach that can be described using the expression ''"Plan a little, do a little"''. Dealing with unclear picture of the whole project, the Rolling-Wave techniques permits to focus on iterative work and frequent updates to the project plan. It permits to focus on what is known, "Plan a little", and work on it, "do a little", until more information becomes available and other data is relevant, so it is possible to evaluate the next "wave" <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>. It is therefore a project planning technique for projects that don´t offer all the data needed to create a plan or a schedule up front: the project plan evolves as more details become clear. In this context, "plan a little" means to create a rough plan for the next wave of work, while "do a little" means to execute the current one. This approach allows the team to move forward with the work for which there is enough data to ensure a clear understanding of. Simultaneously, it is also possible to plan the future work that has still to come. As the project goes on, it is possible gather more information and refine the plan: the key point of the Rolling-Wave planning underlie in this step where the team has the possibility to adapt and refine the plan eventually considering any changes or new information encountered along the way. 

In essence, "plan a little, do a little" is a balance between what is planned and the actions that can be taken, with an emphasis on flexibility and adaptation. This approach allows for a continuous feedback loop where the team can adjust their plans based on what they learn in the execution phase, improving the overall outcome of the project.

== The Rolling-Wave technique: three main principles ==

To apply the Rolling-Wave planning and understand the benefits that this technique can take advantage of, it is important describe the three main principles that undergird Rolling-Wave´s effectiveness <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>.
====Principle One: Project and Product Architecture====
An architecture defines the basic structure of a system, it defines the chunks of a product and project work. Good architectures allow the team to keep a big-picture  perspective even as they drill into details. Good architectures provide a basis for assessing the priorities and aligning activities. The result is improved development speed and flexibility. Product architecture and the project architecture are fundamental to formulating a Rolling-Wave approach <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>.

'''''PRODUCT ARCHITECTURE'''''

Product architecture is the scheme by which the function of the product is allocated to physical components. More precisely it covers decisions regarding the arrangement of functional elements, the mapping from functional elements to physical components and the specification of the interfaces among interacting physical components to meet the desired goals and requirements. The product architecture defines the relationships and interactions between the components and helps to ensure that the product is functional, reliable and usable <ref> Karl Ulrich, ''"The role of product architecture in the manufacturing firm"''], Massachusetts Institute of Technology, Sloan School of Management, December 1993</ref>.

Defined what is the architecture of a product, accordingly to ''"The PDMA ToolBook 3 for New Product Development"'', it is essential to highlight that interfaces are common failure points and, therefore, understanding their structures, functions and limitations can help to manage interface issues and avoid substantial frustration, rework and delay.

For instance, a well-designed product interface enables team members to work together more efficiently by providing a clearer overview of the project, its goals and objectives. In this way, the team members can have a shared understanding of the project, reducing the time needed for communication and collaboration. In the same way, a good product interface provides real-time access to critical project data, which can help team members make faster and more informed decisions. 

Overall, a well-designed product interface can help improve the speed and flexibility of a project, making it more efficient, adaptable and successful.

'''''PROJECT ARCHITECTURE'''''

Project architecture, instead, refers to the overall project or program planning strategy covering topic such as team composition, level of authority, review and approval cycles, roles and responsibilities, risk and issues analysis approach, escalation strategy, etc. In this case rolling wave is best suited for practitioners who have a basic understanding of standard program/project management concepts and principles as it fosters an integrated appreciation of these structures <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>. 

For example, ''"Plan a little, do a little"'' works best when the team has a capability for seeing the big picture and the details so that the project can balance the top-down perspective to the bottom-up <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>.

In particular, the top-down approach is consistent with the idea that top management must have a strict control over the organizational knowledge and, consequently, they must set the goals in line with the overall strategic direction for the company. This implies a pre-defined and clear vision about knowledge in the company, as well as about the strategic goals. In a top-down approach, the ultimate users, at any level of the organization, will therefore simply use it in the way that is prescribed by the top-management <ref name ="Top-Down vs Bottom-Up"> Bolisani Ettore, Scarso Enrico, ''"Knowledge Management and Organizational Learning"'', Volume 3, 2017</ref>.
Conversely, a bottom-up approach implies that the employment and configuration are strictly dependent on the real needs of the users. A bottom-up approach takes the view that valuable organizational knowledge should be shared by users in a sort of social community, and not controlled by the management <ref name ="Top-Down vs Bottom-Up"> Bolisani Ettore, Scarso Enrico, ''"Knowledge Management and Organizational Learning"'', Volume 3, 2017</ref>.

The next video provides a further explanation of the differences between top-down and bottom-up planning: {{#ev:youtube|https://www.youtube.com/watch?v=WLDp82vwVkk|thumb|center}} 


Balancing the two approaches means having employees at any level of the organization that, depending on the specific time through the project lifecycle, can either simply perform what has been decided by the top management or are directly part of the decision-making process. To be a successful planning technique, the Rolling-Wave has to be managed by teams that possess a combination of skills and allow them to view the project holistically, from both a top-down and bottom-up perspective. 
[[File:Top-Down VS Bottom-Up Planning.png | thumb | left | 300px | Top-Down VS Bottom-Up Planning]]

In general, considering the project lifecycle, the proportion of top down thinking is greatest at the beginning, and then diminishes towards the completion of the project. 

Overall, talking about the project architecture, the Rolling-Wave achieves agility because it encourages both a strategic perspective and tactical control over the day-to-day work.

====Principle Two: Uncertainty and Ambiguity====
The Rolling-Wave planning technique is used in project management to deal with uncertainty. Uncertainty means literally without certainty and this implies a lack of predictability of structure and of information. Ambiguity, insetad, refers to a scenario where more than one outcome is possible. Rolling-Wave’s focus is on uncertainty and ambiguity reduction with question like: What do we know? How good is what we know? What don’t we know? How much have we progressed in evaluating what we don’t know?<ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref> <ref name ="PMI Standards"> Project Management Institute, Inc. (PMI)., "A guide to the project management body of knowledge (PMBOOK Guide)", 2021 (Seventh Edition)</ref>

Trying to investigate more in detail the levels of uncertainty, it is possible to split them into four main categories: technical, market, organizational and resource.  

'''''Technical uncertainties''''' relate to the completeness and correctness of the scientific knowledge, the extent to which the technical specifications of the product can be implemented, the reliability of the manufacturing processes, maintainability and so forth <ref name= Innovation> Mark P. Rice, Gina Colarelli O'Connor, Ronald Pierantozzi,''"Implementing a Learning Plan to Counter Project Uncertainty "''], MIT Sloan Management review, Winter 2008</ref>. 

'''''Market uncertainties''''' refer instead to the degree to which customers need and want the product, the value creation and competition. They have to deal with customer acceptance of the proposed functionality, feature set and price. Here can be found all the decisions regarding the extent to which conventional forms of interaction between the customer and the product can be used, the appropriateness of conventional methods of sales/distribution and revenue models and the project team’s understanding regarding the competitiveness with competitors <ref name= Innovation> Mark P. Rice, Gina Colarelli O'Connor, Ronald Pierantozzi,''"Implementing a Learning Plan to Counter Project Uncertainty "''], MIT Sloan Management review, Winter 2008</ref>. 

'''''Organizational uncertainties''''' involve organizational issues both within the project and between the project and its various internal and external constituencies. The first are related to organizational resistance, lack of continuity and persistence, inconsistency in expectations, changes in internal and external partners and changes in strategic commitment. On the other side, there are also uncertainties related to the conflict between the team project and the other units engaged: these are referred to the difficulty of managing the relationship between them <ref name= Innovation> Mark P. Rice, Gina Colarelli O'Connor, Ronald Pierantozzi,''"Implementing a Learning Plan to Counter Project Uncertainty "''], MIT Sloan Management review, Winter 2008</ref>. 

Lastly, '''''resource uncertainties''''' refer to the project teams struggle to attract the resources they required.   They reefers not only to financial resources but also to competencies. Moreover, even when a breakthrough project team is formally established, its funding is generally unstable over time: interest in the project and sponsors come and go. This category is usually closely associated with technical uncertainty<ref name= Innovation> Mark P. Rice, Gina Colarelli O'Connor, Ronald Pierantozzi,''"Implementing a Learning Plan to Counter Project Uncertainty "''], MIT Sloan Management review, Winter 2008</ref>. 

The greater each of these types of product development uncertainty, the more the program needs to use techniques that foster agility, such as Rolling-Wave.

====Principle Three: A functioning team with good leadership====
Experts in new product development have long regarded personal leadership and effective teamwork as key success factors <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>. Indeed, team effectiveness will also lead to better collaboration and communication between team members, which is essential for effective Rolling-Wave planning.

The use of cross-functional teams is a common practice as managers find ways to create a more responsive firm. Members from diverse functional areas contribute unique perspectives to cross-functional teams, which can create innovative teams well-adapt at problem-solving <ref name='Cross Functional team'> Josh Daspit, C.Justice Tillman, Nancy G. Boyd and Victoria Mckee, ''"Cross-functional team effectiveness"'', Team Performance Management, Vol.19, 2013</ref>.  
Cross-functional teams are becoming popular not only to include different perspectives when facing new problems, but also to incorporate the customer point of view and anticipate future problems. Indeed, increasingly for businesses that are adopting agile tools, the development teams are including a knowledgeable representative of the customer as an effective member of the team. This provides relevant feedback on the feature and functions that produce the most value. Because customers can change their priorities, flexible approaches take that dynamic as a given and work to react quickly and effectively <ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>.
Insiders can accelerate the development of the team as effective project reviewers by participating on an oversight board with outsiders who have long and deep experience with decision-making under uncertainty<ref name= Innovation> Mark P. Rice, Gina Colarelli O'Connor, Ronald Pierantozzi,''"Implementing a Learning Plan to Counter Project Uncertainty "''], MIT Sloan Management review, Winter 2008</ref>.

On the other hand, leadership in cross-functional teams is not determined by a single, authoritative position but rather by the abilities of members to collaborate with one another in any given moment.  The elements of team environment work collectively to create a team context that encourages members to provide leadership and accept leadership of other members <ref name='Cross Functional team'> Josh Daspit, C.Justice Tillman, Nancy G. Boyd and Victoria Mckee, ''"Cross-functional team effectiveness"'', Team Performance Management, Vol.19, 2013</ref>.

Therefore, the importance of the team members is strictly related to the effectiveness of the team itself and also to the ability to create an effective team context.

== Implementation of The Rolling-Wave technique ==
To implement the Rolling-Wave technique, it is needed to follow six steps while keeping in mind the three principles behind it previously described. Indeed, project and product architectures, uncertainty, ambiguity and a functioning team with good leadership set the foundation for ''planning a little, and then doing a little''.

File:Rolling-Wave Process.png

The following steps are presented as a guide to apply the Rolling-Wave technique<ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref>:
====Step One: Get the team and strategy in place====
The goal of the first step is to get the team a '''strategy''' right in order to achieve and maintain a robust approach. Thus, Step 1 ensures a charter, an approach to capture and manage requirements, the right people committed to the team, and a good project vision.
 
The '''project charter''' is a document that formally authorizes the beginning of a project and provides the project managers with the authority to start project activities. It outlines the purpose and objectives of the project, the scope of work to be done, the key stakeholders, the resources required and the estimated timeline for completion. It also gives the team resources and the authority to use those resources<ref name ="Charter&Vision def"> Githens, G. D., ''"You can’t be done if you don’t know what done looks like!"'', PDMA Visions Magazine, (January) 2004</ref>. 

The '''project vision''', instead, is a description of the expected outcome in terms of customer benefits<ref name ="Charter&Vision def"> Githens, G. D., ''"You can’t be done if you don’t know what done looks like!"'', PDMA Visions Magazine, (January) 2004</ref>. 

If the organization is not ready, it is needed to invest some effort in organizational development or rethink the strategic intentions in light of the organizational capabilities.

====Step two: Perform Top-Down planning, starting with the Level 1 of the Work Breakdown Structure====
Step two '''establishes the tasks''' and deliverables for the project. The common tool for organizing and managing the project’s work scope is the Work Breakdown Structure (WBS).

A '''WBS''' is a deliverable-oriented hierarchical decomposition of the total scope of work to be carried out by the project team to accomplish the project objectives and create the required deliverables <ref name ="WBS def"> Project Management Institute, Inc. (PMI)., "Practice Standard for Work Breakdown Structures", 2019 (3rd Ed.)</ref> 

In this way, the waves become the planning horizons in which the project will ''plan a little and do a little''. Therefore, project team members should be able to estimate the close-in work with a higher degree of accuracy, decomposing in detail the work within the near-term wave, while, at the same time, longer-term activities are estimated in the range of plus or minus 30 percent.

====Step three: Decompose the first set of "Plan a Little" activities====
[[File:Progressive Planning Elaboration.png | thumb | right | 550px |Progressive Planning Elaboration]]
In this step, the team details individual '''work packages'''.
A work package is defined as the lowest level in a WBS which represent tasks that can be assigned to a team member or department<ref name ="WBS def"> Project Management Institute, Inc. (PMI)., "Practice Standard for Work Breakdown Structures", 2019 (3rd Ed.)</ref>.

Since the Rolling-Wave technique uses a ''Plan a little, do a little'' approach, the team defines the work packages just for the first time horizon. Indeed, while in this step there is a focus in the first of the branches, the work breakdown structure should include also the work that might occur in the later horizons. In this step, it is only necessary to have a general and conceptual understanding of the work involved in the current wave: the goal is to detail the right work at the right time as the project advances in cycles of ''plan a little, do a little''.

====Step four: The baseline====
Step four regards the creation of a '''baseline'''.  A baseline is a committed scope, schedule, budget, risk, etc. against which the project team will monitor its actual performance <ref name ="PMI Standards"> Project Management Institute, Inc. (PMI)., "A guide to the project management body of knowledge (PMBOOK Guide)", 2021 (Seventh Edition)</ref>. The project manager establishes the baseline together with the executives, sponsors, users, project managers and participants. With the new data, it is therefore possible to refine estimations and assumptions, keeping in mind that the most important work of the project team is uncertainty and ambiguity reduction.

====Step five: Execute the planned work====
In this step, the focus is '''inside the wave''': teams work on the tasks assigned previously and the project manager monitors and tracks their progress and performance. The iterative nature of ''plan a little, do a little'' fosters knowledge capture for application in future phases. This learning allows the team to anticipate and avoid future problems, or to react quickly to the risks that the team decides to accept. 

====Step six: Iterate through the planning horizons and close the project====
The last step involves the continuing '''iteration''' of the ''plan a little do a little'' approach until the end of the project is reached. 
The iteration will include the assessment of the team’s learning, the needed work and the planning of the next project’s horizon (refer back to Step 3). 

As the project completes work in the current wave, the attention paid in the next phase increases, rolling through the entire project. Furthermore, a decomposition of the work breakdown structure and the addition of further details as time and cost baselines, will be refined. 
Projects are completed when the product meets the customer’s requirements and when it has completed the necessary administrative processes demanded by organizational policy.

== Real-life case study ==
== Limitations ==

The application of the Rolling-Wave technique helps to overcome the problem of uncertainty in the decision-making process by postponing the decision to a point when there are all the required knowledge. Nonetheless, there are also some disadvantages that could come up with implementing this project management tool. Benefits and shortcoming of the Rolling-Wave technique are sum-up in the following table:<ref name ="Rolling Wave main"> Project Management Institute, Inc. (PMI)., ''"The PDMA ToolBook 3 for New Product Development"'', 2008</ref> 

<span style="font-size:20%">
{|class="wikitable" style="width:100%;"
!style="width:50%;"|'''Benefits'''
!style="width:50%;"|'''Shortcomings'''
|-
|Its agility allows fostering knowledge capture for application in future phases, anticipating and avoiding future problems, reacting quickly to the risks that the team decides to accept
|
Require project team’s understanding and acceptance of the agile principles
|-
|It shortens the duration of front-end planning and gets the individual work teams started with work sooner
|
Not adapt to routine NPD projects where there are few unknowns/incremental innovations 
|-
|Improves the sense of ownership and accountability among team members
|
People have to be self-disciplined and committed to communicate with their teammates
|-
|Promotes an open-minded and flexible project environment
|
Requires trust between people involved

|}</span>

== Annotated Bibliography ==
== References ==
<references/>