Abstract This study uses U.K. audit fee data to evaluate the usefulness of three possible surrogates for audit fees in studies of market concentration (number of audits, client sales and the square root of client sales). No single best measure emerges but concentration measures based upon client sales and the square root of client sales are found to provide consistent overestimates and underestimates respectively of concentration measures based upon audit fees, and thus represent upper and lower bounds for market concentration in auditing. This result should be of use to researchers in countries where audit fee data is not available.
Moizer et al. (Tue,) studied this question.