以文字探勘分析關鍵查核事項與權益資金成本之關聯

Using Text Mining to Analysis the Association of Key Audit Matters and Cost of Equity Capital

本研究透過文字探勘技術，取代傳統關鍵查核事項之項目數與字數計算方式，探討台灣上市（櫃）公司當關鍵查核事項出現什麼關鍵字詞時對權益資金成本之關聯影響。本研究以2016~2018年我國上市（櫃）公司為研究樣本，由於2020年COVID-19逐漸擴散為全球疫情因素，我國因疫情動盪，其所獲得的關鍵查核事項可能隱含更多的雜訊(noisy)，而產生變數衡量偏誤的問題，故樣本選取僅測試到2019年止。以2020年之Jieba斷詞庫與應用詞頻與逆向文件頻率(TF-IDF)之計算，判別查核報告中關鍵查核事項的可讀性，藉以觀察是否影響下一年度之權益資金成本，再計算各產業別關鍵查核事項關鍵字詞之間相依程度(PMI)，決定出該關鍵字詞。研究結果顯示，當會計師所出具的關鍵查核事項之關鍵字為組別1收入類之收入、組別3減損及評價類與組別5、6、7非營運類的關鍵字時會增加權益資金成本，惟組別2減損及評價類之存貨、備抵、金額、變現之關鍵字時，其權益資金成本出現增加與降低權益資金成本之現象。當關鍵字分在組別4資產、減損及評價類時，則降低權益資金成本。

This study employs text mining, as a substitute for the traditional method of counting the number and words of key audit matters (KAMs), to explore the effect of specific keywords in KAMs on the cost of equity capital for listed and over-the-counter companies in Taiwan. The research sample includes companies listed between 2016 and 2018. Owing to the global spread of COVID-19 in 2020 and the resultant turbulence in Taiwan, the KAMs may contain more noise, potentially leading to measurement bias in variables; hence, the sample was only tested up until 2019. Utilizing the 2020 Jieba word segmentation tool and term frequency–inverse document frequency calculations, this study assesses the readability of audit report KAMs to observe their effect on the following year’s cost of equity capital. Through pointwise mutual information, it further calculates the dependency among keywords of KAMs across different industries to identify crucial keywords. The results indicate that when the keywords in KAMs issued by auditors belong to Group 1 (revenue), Group 3 (impairment and valuation), and Groups 5, 6, and 7 (non-operational categories), they increase the cost of equity capital. However, keywords related to inventory, provisions, amounts, and realizations in Group 2 (impairment and valuation) can lead to both increases and decreases in the cost of equity capital. Keywords categorized under Group 4 (assets, impairment, and valuation) decrease the cost of equity capital.