. The goal here is to establish empirical
generalizations about the nature of share–distribution relationships using data from many categories, but we do not attempt to
estimate any causal effect of retail distribution on market share.
Any such estimate would need to rely on a plausibly exogenous
source of variation to disentangle the effect of distribution on
sales from the effect of sales on distribution or to eliminate other
unobserved factors.2 Such effects are interesting and important but they have been estimated by numerous previous studies and
are not the focus of this paper.