The following blog post from 6 weeks ago gives a good introduction to the PID Graph work in the FREYA project:
Fenner, M., & Aryani, A. (2019). Introducing the PID Graph (Version 1.0). https://doi.org/10.5438/JWVF-8A66
Use this link to find all forum posts tagged with pid-graph. Feel free to ask questions or provide comments in the new PID Graph category of the PID Forum.