Problem tree analysis: Urban planning of a railway station

Problem trees may be constructed to aid project design and evaluation. A problem tree consists of constraints linked hierarchically in a tree graph; problems at the lower level contribute or cause problems at the higher level. The problems that define the root causes of the core problem are usually found at the lowest level. Problem trees are one of many forms of tree diagrams (e.g. including objectives trees).

There are two approaches for developing a problem tree:

Group approach
As part of a planning group a workshop is typically conducted with all relevant role players. This can be a community level workshop with people directly affected by the problem or a workshop on a higher level where representatives of the people concerned and of the support system are invited to participate.

Team approach
Through an analysis carried out by a core team of planners, based on the results of a number of problem identification procedures carried out on various levels and with various resource persons.

The identification of problems is most reliable when undertaken in a participatory way. It is important that planners take into account different groups, and consider both general and group-specific problems. For example, men and women often perceive problems in different ways. Problem analysis must go beyond a simple listing. The stakeholders should address questions such as why the problems occur and why they persist. Joint discussion of these questions is, in itself, a valuable forum for learning and can provide vital information. In the problem analysis, problems should be stated as a situation that needs to be improved, and not in a form, which expresses the absence of a solution. For example, rather than saying “a lack of hospitals”, the problem should be “high infant mortality”.

Listing of possible solutions at an early planning stage easily hampers objective and open-minded problem analysis. The “problem tree” technique is a tool that is useful in the identification and analysis stages. Users must have the knowledge and skills to use it and they must also understand the project environment.

The following main steps need to be undertaken to develop a problem tree:

1. List all the problems that come to mind. Problems need to be carefully identified: they should be existing problems, not possible, imagined or future ones. The problem is an existing negative situation, it is not the absence of a solution.
2. Identify a core problem (this may involve considerable trial and error before settling on one).
3. Determine which problems are “Causes” and which are “Effects“
4. Arrange in hierarchy both Causes and Effects, i.e., how do the causes relate to each other - which leads to the other, etc.

Another way of describing the process:

1. Participants briefly review the major problem orally.
2. A tree trunk is drawn and a word or a symbol, which notes the problem is drawn into the trunk.
3. Limbs and leaves are drawn (by the facilitator or, preferably by a participant) in several directions.
4. Participants suggest different dimensions of the problem, and each limb is designated to represent a separate dimension.
5. A root system, symbolizing the causes of the problem, is drawn under the tree.
6. The group suggests possible causes of the problem; each root is marked with a picture or a phrase, which represents a cause.
7. Once the tree is completed, participants discuss the causes, probing into the extent to which each cause determines the major problem. For example, a cause may be major or minor, one-time or permanent.
8. A well-defined problem tree can be a useful place to start an objectives tree. Eliminating the root causes on a problem tree can become the branches of an objectives tree.