依據民國七十八年臺灣同時經營出國旅遊與代辦業務的旅行社普查資料，透過對TMCF與要素份額方程式所組成的近似無關聯立模型進行估計，本文發現，整體而言，該業務組合旅行社具有產品別與射線規模經濟，然出國旅遊與代辦業務間卻顯著地不具有弱成本互補性。但當以出國旅遊人次區分大、中、小型旅行社後，本文進一步發現，中小型旅行社的出國旅遊與代辦業務間具有弱成本互補性及多樣化經濟，而大型旅行社則不具弱成本互補性。因此，為降低平均成本，本文建議，中小型旅行社可朝多樣化經營發展，而大型旅行社可考慮專業化。

Based on a 1989 survey of Taiwan’s tourism industry, iterative SUR results of the model of translog multiproduct cost and factor share equations show that travel agents of simultaneously operating outbound service and agent service do, in general, enjoy product-specific economies of scale and ray economies of scale, and do not enjoy weak cost complementarities. However, small-to-medium-sized travel agents of the above product mix do enjoy weak cost complementarities and economies of scope while large-sized firms still do not enjoy weak cost complementarities. Therefore, this paper suggests that small-to-medium-sized travel agents can pursue diversification, and large-sized ones can pursue specialization to promote cost efficiency.