The two main measures of firm complexity used in previous research are the number of consolidated
subsidiaries (Subs_rt) and the number of industries in which a company is involved in (Segment). Both are
used to measure firm complexity in this study, with a square root transformation to the number of consolidated
subsidiaries performed according to the procedure used by Chen and Zhou (2006), Liu and Hu
(2006) and Li and Wang (2006). To ensure data comparability, we include only those subsidiaries directly
established and held by the sample companies in counting the number of subsidiaries. The number of industries
in which a firm is involved in is determined by the types of business (classified by industry) disclosed in its
annual financial report. We consider such data to be missing if no corresponding data is disclosed in the
annual report, and assign a 1 to Segment if only the main business data classified by product is disclosed. Positive
relationships are expected between these variables and audit fees.