Why using Current Reality Trees (CRTs)?
CRTs use ‘If… Then…’ to answer ‘WHAT to change?’ They are the first step in the application of the TOC thinking processes and lead to the discovery of the root cause, the one item you want to change in order to have the biggest possible impact.
CRTs are basically a root cause analysis. One of the underlying assumptions is that even if you experience many different problems in a particular area they all have only one or a few root causes. CRTs model the cause and effect relationship between the problems (called “Undesirable Effects” or UDEs) and it’s causes.
The task is done when all the UDEs are connected and you can identify the one effect that you need to change in order to have the biggest impact.
CRT Domain Description
The diagram below describes the Domain’s grammar. CRTs start with listing the known Undesirable Effects (UDEs) from one area. Suggestion is to collect between 5 and 10 but no need to stop there.
After that follow the sufficient cause logic to identify the causes. Each cause itself is an effect (desirable, undesirable or simply intermediate). There are two more “causes” which are normally at the bottom of the diagram. These causes are “Given” as things that you cannot change or are “Changeable” as things that you could change. Those are obviously the most interesting causes as a change is most easy by changing what you do and can change.
The Node Types in detail:
|Node Type||Description||Is Starting Point / Successors|
|Undesirable Effect||Undesirable Effects (UDE) are the Starting Node Types for current reality trees. List them first, suggestion is between 5-10. They are caused by other effects of causes.||Yes / All Effects incl. ‘And’|
|Intermediate Effect||Effects that are neither negative or positive on their own. They are caused by other effects or causes.||No / All Effects incl. ‘And’|
|DesirableEffect||A wanted effect. Let’s reinforce this one and cut the negative consequences. They are caused by other effects or causes.||No / All Effects incl. ‘And’|
|Given||Given entities are out of your sphere of influence. They are therefore sometimes called Preconditions. These are always entries to the tree (no predecessors). E.g. Gravity is given and unless you leave earth a given force.||No / All Effects incl. ‘And’|
|Changeable||Changeable entities are those causes that can be changed and should be changed in order to mitigate the problems from occuring (again).||No / All Effects incl. ‘And’|
|And Junctor||Normally in a sufficient cause diagram each cause is alone to create connected effects. The ‘And’ Junctor connects two causes in order to express that something only happens if both causes are taking place.||No / All Effects (excl. ‘And’)|
The Domain setting will highlight those effects (desirable, undesirable or intermediate incl. And Junctor) that are connected to a cause. This way the not-yet-connected effects are highlighted, so you can focus on them.
Background Information on CRT Domain
CRT diagrams were developed as part of the Theory of Constraints by E. Goldratt. More on Theory of Constraints can be found here.