汽車客運業績效評估之研究－資料包絡分析法

Abstract

本論文首先應用資料包絡分析法中之拋物線圖形效率測量法及方向性產出距離函數，來評量台灣汽車客運公司各車站在民營化前後利潤率及風險調整效率變化的情形，研究結果顯示，民營化後利潤率的增加可歸因於技術效率與配置效率兩者均有進步所致，惟配置效率因素所扮演的角色較為重要，而無論是公營的台汽公司或民營的國光公司都有價格扭曲的現象發生，這可能是兩家公司都試圖涵蓋無效率所導致的損失所致；其次，經整合意欲（好的）產出和非意欲（壞的）產出結果，發現台汽民營化後風險調整效率有顯著改進，而此效率改進可能係導致其成本降低的主因。 其次，因多模式汽車客運公司係台灣地區客運業之特色，此種公司同時從事不同模式（如長途客運和市區客運）的運輸服務，其特點為不同模式的服務雖使用不同的生產技術，但卻使用某些共同的投入（如管理人員），因此本論文不僅考慮多模式客運公司內部生產技術之差異，也將運輸服務的不可儲藏性（或稱產銷同時性）涵蓋在內，以便同時測量多模式客運公司的成本效率，服務效果與成本效果；由本論文所應用之多活動資料包絡分析模式與網路包絡分析模式分別與傳統模式比較發現，無論就有效率（果）的公司數，公司效率（果）排序與相互關聯效果等之評量結果顯示，兩種模式與傳統模式間有顯著性差異，且前兩者較後者更為嚴謹。 本論文之主要貢獻可歸納如下： (一) 以往有關客運業配置效率及其相關問題之文獻甚為少見，本論文首度應用拋物線圖形效率法來評量民營化前後利潤率變化問題，這項利潤率指標可被分解為技術效率與配置效率，而配置效率則可進一步用來衡量價格扭曲的程度，此種配置效率不同於傳統方法之處，在於它可僅需藉由觀察收入與觀察成本，而無需價格資訊即可予以衡量。 (二) 本論文首次提出將運輸風險定位為非意欲產出的觀念，應用方向性產出距離函數，整合意欲（好的）產出與非意欲（壞的）產出，用來測量民營化對風險調整效率所產生之衝擊，以有別於傳統客運業績效評估之研究，只著重在意欲產出之重大缺陷上。 (三) 台灣地區客運業，尤其老客運公司，大多屬於所謂多模式汽車客運公司，同時經營公路汽車客運及市區汽車客運，其特色為不同模式服務，係使用不同的生產技術，但卻也使用某些共同的投入，因此，亟不宜如傳統方式將其視為一整體，進行績效評比。本論文應用多模式資料包絡分析法，將共同投入合理配置至不同模式，以求得個別模式之效率值，以提供整體及個別模式之經營績效評比，以及公司內部決策之參考。 (四) 有別於傳統研究忽略運輸服務之不可儲藏性，而分開評量其三種效率（果）之缺點，本論文不僅考慮多模式客運公司內部生產技術之差異，更進一步將運輸服務的不可儲藏性（產銷同時性）涵蓋在內，並應用修正式網路包絡分析法模式將生產與消費技術納入此一模式內，以便同時測量多模式客運公司之成本效率、服務效果與成本效果，以資評比其績效差異。

With the aim of capturing the essence of transit performance, this dissertation addresses four crucial but often neglected issues regarding efficiency measurement for bus transit industry, and thereby using a novel refinement of conventional DEA (Data Envelopment Analysis) models to deal with these issues, in order to shed new light on the facts relevant to transit performance. In contrast to these four issues, this dissertation consists of four essays, with particular reference to the transit performance measure in Taiwan. The first two essays pertain to the impact of privatization on bus firm’s efficiency and talk about to what extent the various efficiency changes before and after privatization. The first essay applies a hyperbolic graph efficiency approach to measure “return to the dollar” at the station-level of Taiwan Motor Transport Company (TMTC) over the pre- and post- privatization period. This measure is further decomposed into its technical and allocative efficiency components. Price distortions can be measured by allocative efficiency using data on observed costs and revenues without requiring explicit information on prices. The decomposition results indicate that both technical and allocative efficiencies contribute to the growth of “return to the dollar”, with the allocative component playing a more important role than the technical component. Perhaps in an attempt to cover the inefficiency-induced losses, both the public and private firms apparently resort to distorting relative output prices with respect to input prices, and the distortion is more pronounced in the private firm than in the public firm. In the second essay, a directional output distance function which incorporates both desirable and undesirable outputs is employed to investigate the effects of privatization experienced by the TMTC. For the first time, the risk-adjusted efficiency change following privatization are estimated by treating transport risk as a joint but undesirable output. The empirical results demonstrate that TMTC’s privatization has produced a distinct improvement in efficiency enhancement and as such may be considered to be a source of cost reduction. The last two essays shift the focus from investigating the influence of privatization on the transit firm to the efficiency measurement of some transportation organizations which engage in various activities (services) simultaneously. This third essay focuses most attention on the technical aspect of how to determine the efficiency of individual services within different but highly homogeneous multimode transit firms which engage in their services with non-identical technologies and use shared inputs. The empirical findings indicate that the multiactivity model used is more demanding than the conventional DEA model. The fourth essay expands the analysis of the third essay to consider both the unstorable characteristics of transportation service and the technological differences within multimode transit firms. The proposed network DEA model allows a representation of both production and consumption technologies in a unified framework and thereby can be used to simultaneously estimate the cost efficiency, the service effectiveness and the cost effectiveness of multimode transit firms. The results obtained from the network model compared to those of a conventional model are quite different in terms of the number of efficient or effective units, rank comparisons of DMUs performance as well as inter-related effects. Throughout the dissertation, the non-parametric technique, also known as DEA, is used as the common approach which integrates the four essays into a dissertation.