Although I am aware that percentage points should be used to describe arithmetical differences between two percent figures, I could not find a satisfying literature reference. Can anyone recommend an encyclopedia with a definition of percentage points (besides wikipedia, I know the entry)?
The wikipedia entry that you mention lists two possible literature references:
- Brechner, Robert (2008). "Contemporary Mathematics for Business and Consumers", Brief Edition. Cengage Learning. p. 190. Retrieved 7 May 2015.
- Wickham, Kathleen (2003). "Math Tools for Journalists." Cengage Learning. p. 30. Retrieved 7 May 2015.