The Scrum Guide

  • 2020 edition
  • “Scrum is now widely used for products, services, and the management of the parent organization”
  • In a complex environment, the world as we know it is subject to change, and the relationship between cause and effect can only be explained in retrospect – probing an environment, sensing and responding (whereas in a complicated environment the relationship between cause and effect requires analysis and/or the use of expert knowledge)
  • Amplify what is working, and dampen what is not.
  • In software development, there is a mix of simple, complicated and complex problems. Scrum fits nicely on the border between helping solve complex and complicated problems.


  • Empirical process control theory – “empiricism”
  • Knowledge comes from experience and making decisions based on what is known
  • Scrum employs an iterative, incremental approach to optimize predictability and control risk
    • Iterative – Progress is made through successive refinement (a first cut of a system is weak in some areas)
    • Incremental – Delivery in pieces of complete subsets of functionality
  • Scrum is both iterative and incremental. See an analogy, below.

The 3 Pillars of Empirical Process Control

  • Transparency – make aspects of the process visible; observers share a common understanding of what is being seen and share a common definition of “Done”
  • Inspection – detect undesirable variances in: the artifacts and the progress toward a sprint goal
  • Adaption – adjust process or materials to minimize deviation from acceptable limits

In Scrum, inspection and adaption take place during the 4 formal events: sprint planning, daily scrum, sprint review and sprint retrospective.

Scrum Values Which Build Trust for Everyone

  • Commitment – People personally commit to achieving the goals of the Scrum Team
  • Courage – The Scrum Team members have courage to do the right thing and work on tough problems
  • Focus – Everyone focuses on the work of the Sprint and the goals of the Scrum Team
  • Openness – The Scrum Team and its stakeholders agree to be open about all the work and the challenges with performing the work
  • Respect – Scrum Team members respect each other to be capable, independent people

The Scrum Team

  • Scrum teams are self-organising and have people with skills across a variety of disciplines that are needed to delivery a final product
  • Being self-organising, they choose how to best accomplish their work rather than being directed by outsiders
  • The scrum team model optimises: Flexibility, Creativity, Productivity
  • There is the development team of 3 to 9 developers, plus a product owner and scrum master
  • The product owner and scrum master might belong to more than 1 (but generally not more than 3) scrum teams.


  • You’re not even criticising Scrum (Chris Cooney)
  • Scrum is not an Agile Software Development Framework (Ron Jeffries)
  • Sprint planning for agile teams that have lots of interruptions (Mike Cohn)
    • x% for corporate overhead (sprint meetings, all-company meetings, emails from previous project, HR training)
    • y% for plannable time (belongs to the team to deliver the sprint goal)
    • z% for unplanned time (emergencies, tasks that get bigger than team thinks/plans, tasks that no one thinks of during the sprint planning meeting)
    • “After each sprint, consider how well the unplanned time the team allocated matched the unplanned time the team needed for the sprint. And then adjust up or down a bit for the next sprint. This is not something a team can ever get perfect…instead, it’s a game of averages.”


  • Rational Unified Process (RUP), Waterfall, Feature Driven Development (FDD), Extreme Programming (XP), Spiral, EVO, Kanban, Crystal, Team Software Process, SAFe …

An Analogy

Scrum is both iterative and incremental.

An analogy could be made to the development of a piece of art for a client.

At first, a hand-drawn sketch of a stick-figure is made on a sheet of A4. The client tells the artist that yes, they want something that looks like a person, indeed, that looks like them.

Okay, the artist uses a pencil to give a better looking sketch of a figure but it still lacks detail especially in the face. The client tells the artist that it is looking more like what is wanted but the clothing should be more from a winter scene that summer. And their pet should be in it too.

The artist takes a photo of the client and their pet dog. The artist shows the picture to them on the camera’s screen. The client tells the artist that they could have done a selfie themselves if that is what was wanted!

So, the artist takes some pastels and makes a colourful, rough drawing on A4 paper. The face has some more detail including the wart the client has on their ear, and there is a dog rubbing up against the client’s leg. “Better”, says the client, “but I really would prefer if it was in 3D”.

The artist asks for payment for time so far spent and a deposit towards materials needed. The artist buys some Plasticine and makes a small figure and a dog. The client agrees this is 3D but it is hardly big enough or professional enough looking for what wanted.

The artist agrees and asks for more money to build a scaled-up version that has more detail. The artist buys some modelling clay and makes a blocky 3D quarter-sized model of a person with a dog at their leg.

The client says that is more like it and says the figure needs to be smoother and resemble their partner instead since, in actual fact, it is the partner who is supplying the money for this. And they want their pet cat not dog in the final piece.

The artist makes another blocky 3D model but this time of the partner and of a cat. The client likes this and asks for a refined version.

The artist asks for some more money to get a better quality material. The artist buys some marble and chisels a bust of the partner, making sure to get a lot of detail in the eyes and nose but leaving other parts of the head somewhat blocky.

The client likes this, and decides they only want a bust, not a whole figure. The artist refines the rest of the bust, filling in the features of the mouth, ears and neck but leaving the hair for now.

The client is really liking the bust! “But what happened to the cat?”, they ask.

The artist asks for a final payment and goes away to chisel the remainder of the head, filling in the hair. The client laughs hysterically when presented with the final bust and pays a bonus to the artist. The client’s partner also laughs when they see what their ‘hair’ really is.