Information on audit quality may also be inferred from auditor–client contracting
features, such as audit fees. Audit fees are used to proxy for audit quality because they are expected to measure the auditor's
effort level, which is an input to the audit process that is intuitively related to audit quality.39 A distinguishing feature of
audit fees is that they are the outcome of both supply and demand factors. Auditors cannot unilaterally charge higher fees
for additional effort unless there is a corresponding increase in client demand for the additional effort. As a result, audit fees
are used in both demand and supply studies. For example, in demand studies, audit fees are often used to test whether audit
committee competencies are associated with audit quality. In supply studies, audit fees are most commonly used to test
whether audit quality is associated with litigation risk, and whether Big N or industry specialist auditors are associated with
audit quality