Causal Loop Diagrams (CLD), is a tool used in system dynamics to develop an understanding of complex systems. This blog post by William Rushing, explains the structure of CLDs and provides figures to demonstrate. Variables are gradually added to the CLD, showing the affects and impacts they have on one another.
Rushing, W. (2010) Causal Loop Diagrams: Little Known Analytical Tool. Six Sigma. Retrieved from http://www.isixsigma.com/tools-templates/cause-effect/causal-loop-diagrams-little-known-analytical-tool/