There is no general answer to this question except: as deep as necessary to serve your purpose and as deep as necessary for you to feel comfortable with. Which is not very helpful to beginners.
In order to give more practical advice, let’s consider two cases:
- Goal Tree used to (re)define a strategy at executive level, used with the Logical Thinking Process
- Goal Tree used at any level as a stand-alone tool, with an action plan
1. Goal Tree used to (re)define a strategy at executive level
Dettmer introduced the Goal Tree as a logically sound and robust benchmark prior to assess the Current Reality and work to solve the problems that hinder the organization achieving its Goal. It starts with the Goal, which is a lighthouse guiding all initiatives and onto which to align all contributions. The Goal Tree is therefore the first logical tree to be built in the process called… Logical Thinking Process.
The Goal, purpose or “big picture” is defined by the system owner, the founder(s) or those having delegate power to lead the organization toward its Goal. These top most executives may not want nor have time to be dragged down into each detail of all the Necessary Conditions for the Goal to be achieved.
Therefore they will be highly interested in the answer to the question how deep should a Goal Tree go?
The answer: In order to feed the Current Reality Tree, the Goal, the 3 to 5 Critical Success Factors and the two layers of NCs beneath them are enough. All of them will become entities of the CRT.
Indeed, experience confirms that going this deep is enough. The CRT building methodology helps finding the critical root cause(s) and the links between all these entities. As neither the Goal nor CSFs nor the few high level NCs are achieved yet, the building of the CRT starts by expressing the Undesirable Effects (UDEs), which are deviations from the desired achievement. Logical analysis leads to the Critical Root Cause(s) without needing a complete detailed Goal Tree.
Even it is not required, if someone feels more comfortable with a more detailed Goal Tree and can afford the time building it, let him/her go for it.
2. Goal Tree used at any level as a stand-alone tool
A Goal Tree can be used as a stand-alone tool and one does not need to go through the whole Logical Thinking Process for preparing an action plan. This could be the case of a new activity starting from scratch in which no previous existing state has to be improved. It can also be a project for which all elements are represented in a Goal Tree and the Tree is used to check the completeness of the tasks and Necessary Conditions envisioned. Finally it can be an improvement in a department or organization in which there are no major complex problems to solve, not requiring to go through the whole LTP.
In such cases, how deep should the Goal Tree go?
Well, basically a Goal Tree is not limited, but soon practical limits will surface, starting with the number of CSFs. I keep recommending to limit CSF to five, which are sufficient in most cases.
>Read more about defining CSFs
Soon, the limited number of CSFs will lead to a fair number of first level NCs, followed by an even greater number of level 2 NCs and so forth.
The number of levels or depth of the tree depend how fast the breakdown reaches the trivia level. In an established business there is no need to describe what is the very essence of it.
For example in manufacturing it is not necessary to set “master milling techniques” or “have expertise in wave soldering” if it’s already part of the daily operations.
It is different when a new manufacturing way is envisioned, as for example manufacturing parts not by cutting material away but adding it, like in 3D printing for example. If these new techniques are not yet known within the company, acquiring them and mastering them may be set as Necessary Conditions.
In general, digging deeper into NCs is meaningless once the NCs do not provide helpful Intermediate Objectives to align contributions anymore.
Being too specific makes the Goal Tree difficult to maintain and giving too many precise requirements to staff reduces the interest in the job as everything seems to be prescribed. Conversely, giving higher level objectives to staff and asking them to work out the plan to achieve them is motivating and helps buy-in as staff gets involved in the project definition.
>Read more about Goal Tree as vehicle for change management
There is no absolute limit nor any general recommendation about depth of Goal Tree, except people must be comfortable with.
Cascading objectives in an organization
When cascading objectives in an organization, my rule of thumb is to try limiting to five or six levels deep: Top management sets the CSFs, head of departments the first and second level of NCs, middle management the next two or three levels of NCs.