Things become more complicated when we do not want to assume that the
true values of the uncertain attributes are perceived among consumers as being
mutually independent: in many real-world situations, uncertain attributes
like price may for example be (perceived to be) positively correlated with uncertain
quality-related attributes, as a higher price may signal higher quality of the
good (e.g. Wolinsky, 1983; Milgrom and Roberts, 1986).