Input-based measures evaluate audit quality using observable inputs to the audit process. However, because inputs may
not directly translate into outputs, they are relatively noisy audit quality measures. In this section we discuss the two
categories of input-based proxies commonly used in the literature: auditor-specific characteristics such as auditor size
(captured by Big N membership) and industry specialization, and auditor–client contracting features such as audit fees.37
We begin by describing each measure and the types of studies that tend to use it. We then evaluate the unique strengths and
weaknesses of each measure, including issues related to measurement. Because input-based proxies do not capture auditor
misconduct and are all based on actual observed characteristics, they do not vary on the dimensions of directness,
egregiousness, or actual-versus-perceived quality.