Table 2.

Relationship between α value and Zipf's principle of least effort

α value	Examples in literature	Least effort for
α < 1.6	Advanced schizophrenia (Piotrowska and Piotrowska, 2004; Zipf, 1949), young children (Brillouin, 2004; Piotrowska and Piotrowska, 2004)	–
1.6≤ α < 2	Military combat texts (Piotrowska and Piotrowska, 2004), Wikipedia (Serrano et al., 2009), Web pages listed on the open directory project (Serrano et al., 2009)	Annotator
α = 2	Single author texts (Balasubrahmanyan and Naranan, 1996)	Equal effort levels
2< α ≤ 2.4	Multi author texts (Ferrericancho, 2005)	Audience
α > 2. 4	Fragmented discourse schizophrenia (Piotrowska and Piotrowska, 2004)	–

For α values < 1.6 or > 2.4, we have no corresponding effort–level as the text is treated as incomprehensible.