Often a quality improvement necessitates modifications of varietal product
features. This paper studies firms' incentives to provide quality when this
decision affects the goods' degree of perceived horizontal differentiation
. We find that the quality level hinges crucially on the interaction betwee
n the quality and the varietal product attribute, We examine the outcome of
a game where firms decide on quality and price relative to what a social p
lanner would desire, If the interaction between quality and perceived horiz
ontal differentiation is sufficiently positive, we find for the sequential
game 'quality then price' that the private incentives to provide quality ar
e excessive relative to the social optimum. As a result the level and the d
irection of interaction between the attributes determines whether there is
excessive or insufficient provision of quality. (C) 2001 Elsevier Science B
.V. All rights reserved.