Triage – Decision Trees

Triage – Decision trees: The pitfalls

Triage systems –and other decision trees– are commonly used to direct actions in a process.

Sometimes it is a simple sieve; in other cases it is a multi-dimensional ‘funneling system’ that leads the user through a series of questions to bring him to the one and only possible answer. Remember in biology lessons, the plant determination guide?

1. Ease of use

Many triage procedures are ‘written text’ and may be absolutely correct. However since our brain is much more powerful in visual handling than text handling, it would help to present the ‘decision making process’ in a visual manner.

The following example is based on a Dutch tax form.

triage_example.jpg First the whole process was precisely and in detail designed, including all ‘what if scenarios’. This was brought into a PSD that was very much correct and complete, but also became quite difficult to read. Based on the insight now gained, de relevant decision points where transformed into understandable and unambiguous questions. Those question where presented in a visual manner to the final user.

In the design-state, the use of PSD can dramatically ease up the insight of the process; compare those two examples:


A simple sieve in a flowchart…. ….the same sieve in PSD
triage_flow_320.png triage_psd_320.png

2. Questions are unambiguous

“The patient can go to blood test” Yes – No
Does this mean “The patient is able go there?” or does it mean “we are ready to send the patient there”.

You might recieve different answers, depending the pespective the user is answering the question from! This should be prevented at all circumstances!

3. Questions are easy to understand

“Do you want to prevent to get no sugar with cream?”

Now what are you going to prevent exactly?

Sometimes it is difficult enough to ansewer the question… them why make a riddle from a question?

4. Structure of design

A good triage is full- ánd fool proof… so it should work at all circumstances. Things tend not to go wrong when everything is OK. A triage should also, no precisely work when things gó wrong, under pressure, when there is panic!

  • What do I have to do if I can not answer one of the questions?
  • What should I do if I made a wrong decision at any point?
  • What should I do if the answer is neither A or B but an unexpected C?
  • Is it possible to answer a specific question at this specific moment in the triage? (“If you do not like the product you may return it in an unopened package”)

To achieve a proven correct structure to the triage process, a PSD is a tremendously strong tool!

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