頻譜拍賣設計之理論與實驗研究－從Ausubel到CCA

Abstract

Ausubel (2004, 2006)設計價格鐘拍賣制度，以類似『機會成本』概念決定商品分配；各回合得標數量是由總供給減去其他投標者需求數量來決定。這兩篇文獻以理論證明此拍賣制度可以達成效率分配，本文則以實驗方法檢驗受試者行為是否與理論預測相同。實驗結果發現Ausubel拍賣可以達成接近極大值之分配效率，但是在正縱效情況下效率較低。並且因為沒有組合投標機制，Ausubel拍賣仍然有曝險問題，故受試者可能發生虧損。2013年英國4G釋照採用複雜的組合價格鐘(combinatorial clock auction, CCA)制度，本研究結果讓我們充分理解CCA設計之意義：基本競標回合採用多回合上升價格鐘方式具有重要的資訊揭露意義，若無此動態過程，單回合拍賣會有巨大的風險與不確定性。價格發現過程完成後，業者可在CCA的最後附加競標回合內投下一次密封組合標，故投標者可以充分表達其對各種組合之願付標價，以避免曝險問題。CCA兼具多回合上升標價格發現以及單回合組合標效率分配二者的優點，這應該是許多先進國家在4G釋照時都採用CCA制度的理由。

Ausubel (2004, 2006) designed dynamic price clock auction systems, in which the quantity allocation principal was similar to the opportunity cost concept; bidders were allocated the quantity that was not demanded by others. It could be proved theoretically that the Ausuble auction mechanisms could achieve efficient allocation. This paper conducted experiment to check whether subject behavior supported theoretical predictions. We found that Ausubel auction could achieve a high level of efficiency, but less so when there existed positive synergy. However, without combinatorial bids, bidders would still face exposure risk, and hence might incur losses. In 2013 Ofcom adopted the CCA (combinatorial clock auction) system to award the British 4G licenses. This research supports the complicated design of CCA. The dynamic clock phase of the primary bid rounds serves as the price discovery process, while the supplementary round provides bidders one final chance to submit combinatorial bids to alleviate the exposure risk. Therefore, CCA combines the advantages of dynamic auction and combinatorial bids. Such favorable features may explain the popularity of CCA among many countries.