Concentration ratios vary greatly among manufacturing industries.
These data show the share of total annual sales (in dollar terms)
accounted for by the four largest firms in the industry.
(Source: Author’s calculations based on data provided by Statistics Canada.)
Defining the Market
The main problem associated with using concentration ratios is to define
the market with reasonable accuracy. On the one hand, the market may be
much smaller than the whole country. For example, concentration ratios
in national cement sales are low, but they understate the market power of
cement companies because high transportation costs divide the cement