企業多角化程度的衡量－以赫氏指標為例

Abstract

Hall (2005)與Chen, et al. (2010)發現利用赫氏指標 (Herfindahl-Hirschman Index, HHI)衡量技術規模較小企業的技術集中度時，容易產生偏誤。 本文透過討論赫氏指標的演進，討論為何赫氏指標在衡量技術規模較小的企業時容易發生偏誤，並且設計出衡量此一偏誤的方法。透過Qualcomm和Mediatek兩家企業的實際資料，本文能夠利用預先設定的誤差標準，最小赫氏指標誤差距與最小赫氏指標誤差率，判斷能否以赫氏指標衡量該企業的技術集中度。 利用本文發展出的轉換後赫氏指標(Herfindahl-Hirschman Transformed Index, HHT)，我們能夠較為準確的衡量技術規模較小企業的技術集中度，以解決赫氏指標在衡量這些企業技術集中度時，會有大量誤差的問題。

Hall (2005) and Chen, et al. (2010) have discovered that it is easily getting a bias result when using Herfindahl-Hirschman Index (HHI) to measure the technology concentration of small-patent-scale firms. In order to understand how serious the bias is, we established a method to calculate the bias. We have shown that we could distinguish the technology portfolio of firms, whether it is able to be unbiasedly measured by HHI or not, through two new indicators we developed, HHI-error distance and HHI-error ratio, by adapting the real patent data from two semiconductors companies, Qualcomm and Mediatek. Furthermore, we have constructed a new index, Herfindahl-Hirschman Transformed Index (HHT) to measure the technology portfolios of small-patent-scale firms. We have shown that HHT could unbiasedly measure the technology concentration of small-patent-scale firms.