Causal loop diagrams

A visual way of representing systems: their elements, relationships between elements, and feedback loops resulting from those relationships. To draw a causal loop diagram:

1. Identify the elements: these are the nouns in the system, e.g. “bank balance” and “earned interest”. Remember that in human systems the elements aren’t only things we can point to, but can also be abstract (e.g. “satisfaction”) or even imaginary (“perceived threat”).
2. Identify their relationships: represent causal relationships with an arrow. Since your bank balance determines how much interest you earn, draw an arrow from “bank balance” to “earned interest”. And since interest earned affects your balance, draw an arrow going the other way too.
3. Identify the direction of those relationships: for each arrow, consider whether an increase in the source of the arrow leads to an increase in the element at its destination. If so, mark the arrow with a “+” or “s” (for “same” direction). If not, mark the arrow with a “-“ or “o” (for “opposite” direction).
4. Identify the types of feedback loops: for any feedback loops (circles) in your diagram, identify whether they are balancing or reinforcing. A neat trick: if there are an even number (or zero) of opposing relationships in the loop, then it’s reinforcing. If there are an odd number of opposing relationships, it’s balancing.

Delays

Arrows in a causal loop diagram will sometimes include a pair of lines intersecting them to indicate a delay between the causal event and when its effects can be observed. Delays come in four types:

• Physical: the delay (due to the laws of physics) in moving physical from one place to another, e.g. shipping time is the delay between you making a purchase and your satisfaction with the item
• Transactional: time time it takes to make some change, e.g. wanting a new job and getting one are causally related, but with the delay of going through the search, application, interviewing, and negotiation processes
• Informational: new information can lead to changes in a system, but information takes time to propagate through a system.
• Perceptual: the delay in a human system between conditions changing and the people within that system realizing that conditions have changed. Beliefs and ideologies come into play here

Source

Summarized from The Systems Thinker.

Tools

Loopy, a beautiful interactive tool for visualizing feedback loops in motion. See my friend Miles’s example visualizing the relationship between detail in software support requests and the productivity and morale of the support team. One of Loopy’s own examples:

Examples

• An organization called Democracy Fund has compiled causal-loop diagrams describing aspects of the American political system.