| 摘要: | 本篇論文主要是關於網路拍賣賣方行為的研究，包含賣方拍賣方式的選擇與動機，以及保留價格的設定。首先，我們研究拍賣方式對於最終拍賣結果的影響。其次，我們討論不同拍賣方式與保留價格之間的關係。最後，我們也進一步分析不同保固期限與不同產品來源－公司貨與平行輸入－對於拍賣交易結果的影響。
第一項議題是以實證方式來探討網路拍賣的賣家在銷售相同產品時，為何會採用不同的拍賣方式？以及當賣方選擇某種特定拍賣方式之後，對於拍賣結果的影響。首先，我們假設賣方採取不同拍賣方式的理由，在於賣方的經驗和賣家的存貨多寡。利用這兩項賣方的特性內生化賣方三種拍賣方式的選擇：純粹拍賣、有立即購買價拍賣及固定價格拍賣。然後，比較這三種拍賣方式在成交機率、成交價格和實際成交天數上的差異。我們的實證結果指出，固定價格拍賣有最高的成交價格，但是它的成交機率卻是最低。然而，純粹拍賣與有立即購買價拍賣，雖然有相同的成交機率與成交價格，但是有立即購買價拍賣的實際成交天數是最短的。這些結果強烈顯示成交機率與成交價格之間存在一抵換關係。同時，我們也發現風險與時間偏好是賣方採取立即購買價拍賣的重要考量因素。
至於第二項議題，我們提出一個簡單的理論模型，以賣方的耐心程度來內生化賣方對於拍賣方式的選擇。我們理論證明根據賣方對時間偏好程度的不同，網路拍賣的三種拍賣管道（純粹拍賣、有立即購買價拍賣及固定價格拍賣）都可能為最適的拍賣方式。同時，理論也預期固定價格拍賣的最適保留價格會比有立即購買價拍賣的最適保留價格來得高，而純粹拍賣的最適保留價格是最低的。我們也利用 eBay 的實際拍賣資料，驗證前述理論預期。此外，以賣方的存貨多寡作為賣方耐心程度的代理變數，實證結果也指出最適的保留價格與賣方時間偏好程度之間，呈現反向的關係。
最後一項議題，主要是利用台灣 Yahoo! 拍賣的Nikon 相機資料，調查公司貨與平行輸入產品在最終成交結果有無差異存在。我們發現平行輸入與公司貨的產品，除了賣方所提供的保固期限不同之外，賣方也會選擇不同的拍賣方式來銷售。由此可知，產品來源和賣方拍賣方式這兩項因素都有可能會影響到成交機率與成交價格。我們的實證結果指出，當模型考量賣方拍賣方式選擇的內生性和其他特徵變數之後，相對於平行輸入的產品，公司貨產品的成交機率高了 7%，而成交價格占廠商建議售價的比值約提高 9.3%。同時，我們發現少數沒有經驗的賣家，會試圖將平行輸入品以純粹拍賣的方式銷售，並且設定高的起標價格來銷售。因而造成水貨的成交機率比公司貨產品的成交機率來得低。如果我們不考慮到這些採用純粹拍賣的賣方時，公司貨的產品仍然有較高的成交價格，但是其成交機率與平行輸入產品沒有顯著差異。
This dissertation is mainly focused on the seller’s behavior in Internet auctions, including the choice of listing formats, the setting of reserve price. I study the effects of the seller’s listing-format choice on auction outcomes and the relationships between the reserve prices and listing formats. Furthermore, I also investigate the influences of the different duration of warranty and the different product source — the parallel imports and the authorized products — on transaction results.
The first part empirically studies why the sellers of identical commodities adopt different listing formats in online auctions, and the consequences thereof. We postulate that the sellers adopt different listing formats because of the differences in their experience and inventory size. We first use these two characteristics to endogenize the seller's choice between three listing formats: fixed-price posting, buy-it-now (BIN) auction, and pure auction. We then estimate the differences in sales rate, transaction price, and sale duration between the three formats. We find that the fixed-price format results in the highest transaction price and the lowest sale rate. The pure and BIN auctions have similar sales rate and transaction price, but the latter has the shortest sale duration among all three. These results strongly suggest that there is a tradeoff between price and sale probability for the seller's choice between an auction (including pure and BIN) and a fixed-price listing, and that both risk and time preference considerations are important in adopting BIN.
As to the second part, we propose a simple model of auctions with an impatient seller who chooses the reserve price and the BIN price to maximize revenue. The three main sales channels in the online auction (the pure auction, the BIN auction, and the fixed-price sale) are each shown to be an optimal solution for the sellers with certain degrees of time-preference. The theory also predicts that the optimal posted price for the fixed-price listing is greater than the optimal reserve price for the BIN auction, which in turn is greater than that for the pure auction. This prediction is confirmed by data from eBay's auction of iPods. Using the seller's inventory as a proxy for his degree of time-preference, the data also confirm the theoretical prediction that there is an inverse relationship between the optimal reserve price and the seller's time impatience.
The last part investigates whether there exists any difference in transaction results between commodities which are sold by authorized sellers and those which are parallel imports by using data from Taiwan's Yahoo! auctions of Nikon cameras. We find that the parallel imports and the authorized products differ not only in the warranty duration offered by the sellers, but also in the formats in which they are listed, both of which substantially affect trade probability and transaction price. We show that, after taking into account the endogenous choice of listing formats and the characteristics of the sellers and the items, an authorized product has a 7% higher trade probability than that of a parallel import and, if there is a sale, the transaction price as a ratio of the manufacturer's suggested retail price is 9.3% higher. A small number of less experienced parallel import sellers, in an attempt to maintain a price comparable to the authorized product, list their items in pure auction with unusually high starting bids. This accounts for the overall lower trade probability for the parallel imports. If we disregard these sellers who adopt pure auction, the authorized product has higher transaction price than, but about the same trade probability as the parallel import. |
