  Confirmation bias is a cognitive bias that adversely affects management
decisions, and mathematical modelling is an aid to its detailed understanding.
Bias in opinion update about the value of a parameter is modelled here assuming
that observations are discounted depending on their distance from prior
opinion. The models allow belief persistence, attitude polarization, and the
irrational primacy effect to be explored. A general framework for exploring
large-sample properties of these models is given, and an attempt made to
classify the models. An interesting result is that in some models the influence
of an observation always increases with distance from the prior opinion,
whereas in others observations greatly at odds with prior opinion are given
very little weight. The models could be useful to those exploring these
phenomena in detail.
