Let me be frank; I think “The conjunction fallacy and interference effects” (ungated version) is a horrible misuse of math and indicates an embarrassing failure of peer review.
The author, Riccardo Franco, introduces a parameter that does doesn’t have any foundation in the phenomena it is trying to explain, nor is it shown to aid in modeling.
Please tell me I’m missing something.
What? You’ve never heard of the conjunction fallacy? It is yet another cognitive bias studied by Amos Tversky and Daniel Kahneman. They gave people the following problem (quoting from Wikipedia):
- Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.
- Which is more probable?
- Linda is a bank teller.
- Linda is a bank teller and is active in the feminist movement.
85% of those asked chose option 2.[2] However the probability of two events occurring together (in “conjunction”) is always less than or equal to the probability of either one occurring alone—formally, for two events A and B this inequality could be written as 
, and 
Franco, R. (2009). The conjunction fallacy and interference effects Journal of Mathematical Psychology, 53 (5), 415-422 DOI: 10.1016/j.jmp.2009.02.002
Permutations 