The Boone Indicator
The central idea behind the Boone Indicator, as proposed by Boone (2000) and Boone,
van der Wiel, and van Ours (2007), is that a more efficient bank is more profitable than
less-efficient banks. That is, markets map efficiency differentials into profit differentials.
Boone (2000) is able to show within a broad set of theoretical models that this mapping
of efficiency differentials into profit differentials becomes steeper as competition increases.
That implies that the more competitive the market, the more harshly a bank is punished
for inefficiencies in terms of relative profits. This last result enables the measurement of
competition via the the response of profits to changes in marginal costs. The economic
argumentation behind the idea of measuring the degree of competition by analyzing the
relationship between profit and efficiency ratios is based on the selection effect of competition
stressed by Vickers (1995). This line of thinking holds that “competition causes
efficient organizations to prosper at the expense of inefficient ones” (Vickers, 1995, p.1).
Boone (2000) argues that this selection effect is constituted by the reallocation effect of
competition. A rise in competition reallocates output from less-efficient to more-efficient
banks, measured by marginal costs. Firms with lower marginal costs are able to offer
their product at a lower price. Increasing competition allows efficient banks to use their
cost advantage more aggressively, which draws customers away from banks with higher
marginal costs. This effect increases the output of more-efficient banks. It is this reallocation
of output that raises the profits of efficient banks relative to less efficient competitors.
The above discussion supports the following log-linear relationship between relative profits
and relative efficiency, measured by marginal costs (see also Boone, van der Wiel, and
van Ours (2007)):