Test Driven Development: By Example

Appendix I

Influence Diagrams

This book contains many examples of influence diagrams. The idea of influence diagrams is taken from Gerald Weinberg’s excellent Quality Software Management series, particularly Book 1: Systems Thinking.¹ The purpose of an influence diagram is to see how the elements of a system affect one another.

Influence diagrams have three elements:

• Activities, notated as a word or short phrase

• Positive connections, notated as a directed arrow between two activities; meaning that more of the source activity tends to create more of the destination activity, or less of the source activity tends to create less of the destination activity

• Negative connections, notated as a directed arrow between two activities with a circle over ...