To assess the performance of third-party sellers relative to Amazon, this study estimates the effect of different sales strategies on Amazon's reported best sellers rank (BSR) of ground coffee in the USA and Canada and red wine in the United Kingdom using a fixed-effects model. The products are either ‘sold and shipped by Amazon’ (Amazon), ‘sold by the third-party seller and fulfilled by Amazon’ (FBA), or ‘sold and fulfilled by a third-party merchant’ (FBM). For each of the grocery products and in all empirical specifications, FBM increases the BSR, reducing the relative sales performance of the product in its category. Specifically, FBM increases the BSR of grocery products by 60% relative to Amazon whereas the effect of FBA on BSR is mostly indistinguishable from the effect of Amazon on BSR. These results suggest that Amazon and FBA mostly perform equivalently, but both sales strategies outperform FBM. However, whether the relatively poor performance of the third-party (FBM) shippers and sellers is due to unfair competition by Amazon remains an open question.

中文翻译：

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竞争激烈的市场还是不公平的竞争对手？亚马逊及其畅销书排名分析

为了评估第三方卖家相对于亚马逊的表现，本研究使用固定的-效果模型。产品要么是“由亚马逊销售和发货”（Amazon）、“由第三方卖家销售并由亚马逊配送”（FBA），要么是“由第三方商家销售和配送”（FBM）。对于每种杂货产品和所有经验规范，FBM 都会增加 BSR，从而降低产品在其类别中的相对销售业绩。具体来说，相对于亚马逊，FBM 将杂货产品的 BSR 提高了 60%，而 FBA 对 BSR 的影响与亚马逊对 BSR 的影响几乎没有区别。这些结果表明，亚马逊和 FBA 的表现大多相当，但两种销售策略的表现都优于 FBM。然而，第三方（FBM）托运人和卖家表现相对较差是否是由于亚马逊的不公平竞争仍然是一个悬而未决的问题。