Evaporating Cloud

The Evaporating Cloud is one of the six Thinking Processes in the Theory of Constraints initially developed by Eliyahu M. Goldratt to enable the focused improvement of any system (especially business system). The Evaporating Cloud is also referred to in the literature as The Conflict Resolution Diagram.

The Evaporating Cloud is suited to finding a solution to conflict between two parties or two points of view. The method requires the participants to find 'win-win' solutions because it emphasizes that both parties are trying to reach the same ultimate goal.

This understanding of conflict can be diagrammed as follows:

  B <——  D                          B <—— Some D
 /       ↑                         /        ↑ 
A         conflict       OR       A          conflict (not enough D)
 \       ↓                         \        ↓
  C <—— Not D                       C <—— Some more D

Where A is the Objective, B and C are Requirements, and the D nodes are Prerequisites that are in conflict. The lines or arrows connecting the nodes represent the rationale or causal assumptions that are used to link the nodes.

When writing the cloud, the arrows should be read as “in order to” or “because” or “so that”. For example: “In order to achieve A we require B because there is no way we can have A without B.” Or: “There is no way we can have D and Not have D at the same time.”

Steps in problem solving:

1. Decide that you really must solve the problem.
2. Draw the cloud and define clearly the conflict, the common goal, and the intermediate assertions.
   • What does each party want? This will be boxes D and NOT D. Clearly identify why they can’t both be met.
   • Identify the underlying requirements--the reason why each party needs what they want. These are boxes B and C.
   • What is the common goal that ties B and C together? This can be difficult to determine, but unless there is a common goal there would be no conflict! Maybe it’s as simple as “we both keep our jobs”; but there has to be something.
3. Obtain agreement that the definition is correct.
4. Look “under the arrows” and review the causal assumptions.
5. Challenge each of the causal assumptions.

Example

Goldratt has illustrated the use of the evaporating cloud technique in a discussion of the Economic production quantity model, as applied to a production line. ^[1] The prerequisites are to run large batches (node D) and yet to run small batches (node Not-D). These are clearly in conflict. The requirement that D is trying to meet is to reduce setup cost (node B), whereas the Not-D prerequisite is intended to reduce carrying cost per unit (node C). Both requirements are aimed at the objective (node A): to reduce cost per unit.

The assumed causal reasoning between the conflicting D nodes is something like “there is no way we can run large batches and small batches at the same time.” This conflict can be challenged by distinguishing between production batch size (between setups) and transfer batch size (between workstations), and so allowing different sized batches for different purposes.

Core Conflict Cloud

The Core Conflict Cloud is an Evaporating Cloud that emerges from analysis of a Current Reality Tree, which is one of the Thinking Processes introduced in Eliyahu M. Goldratt's novel It's Not Luck.

References