This web page by Edward Tufte provides guidance on the use of slope graphs.
Through the use of detailed examples and graphics the general theory and practice of slope graphs is clearly articulated.
Sources
Tufte, E., (2014), Slopegraphs for comparing gradients: Slopegraph theory and practice. Retrieved from: http://www.edwardtufte.com/bboard/q-and-a-fetch-msg?msg_id=0003nk
'Slopegraphs for comparing gradients: Slopegraph theory and practice' is referenced in:
Method