Table 3.
p-validity | Coherence | |||
---|---|---|---|---|
Inference | Min | Max | Min | Max |
MP | max{x+y−1,0} | 1 | xy | 1−y+xy |
DA | max{x+y−1,0} | 1 | (1−x)(1−y) | 1−x(1−y) |
AC | max{x+y−1,0} | 1 | 0 | min{y/x,(1−y)/(1−x)} |
MT | max{x+y−1,0} | 1 | max{(1−x−y)/(1−x),(x+y−1)/x} | 1 |
Notes: (1) In each case x = The probability of the major premise, if p then q, and y = the probability of the relevant minor premise, i.e., P(p) for MP, P(not-p) for DA, P(q) for AC, and P(not-q) for MT.
(2) P(if p then q) = P(q|p) is assumed for calculation of the coherence but not p-validity intervals.
(3) For both measures, a “hit” is defined as an estimated conclusion probability which is between the minimum and maximum values shown in the table.