Abstract

“Brushing”---the practiceof online merchants placing fake orders of their own products to artificiallyinflate sales on e-commerce platforms---has recently received widespread publicattention. On the one hand, brushing enables merchants to boost their rankingsin search results, because products with higher sales volume are often rankedhigher. On the other hand, rankings matter because search frictions faced bycustomers narrow their attention to only the few products that show up at thetop. Thus, fake orders from brushing may affect customer choice. We build astylized model to understand merchants’ strategic brushing behavior and itswelfare implications. We consider two competing merchants selling substitutableproducts (one of high quality, the other of low quality) in an evolutionarysales-based ranking system that assigns a higher ranking to a product withhigher sales. In principle, such an adaptive system improves customer welfarerelative to a case in which products are randomly ranked, but it also triggersbrushing as an unintended consequence. Since the high-quality merchant receivesa favorable bias in the sales-based ranking, he mainly has a defensive brushingincentive, whereas the low-quality merchant mostly has an offensive brushingincentive. As a result, brushing is a double-edged sword for customers. It maycause customer welfare to be even lower than what it would be in arandom-ranking system, but in some other cases, it can surprisingly improvecustomer welfare. If brushing is more difficult for merchants (e.g., due totougher regulations), it may make customers worse off as it attenuates brushingby the high-quality merchant but induces the low-quality one to brush moreaggressively. If search is easier for customers (e.g., due to improved searchtechnologies), it can actually hurt them as it may disproportionately discouragethe high-quality merchant from brushing.

Time

6月19日（星期三）14:00—16:00

Speaker

Dr. Luyi Yang is an assistant professorof operations management and business analytics at Johns Hopkins University,Carey Business School. His research interests lie in consumer-driven serviceoperations, business model innovation, applied mechanism design, digitalmarketplace, and operations-marketing interface. His research has beenpublished in Management Science and recognized by several best paper awards.Luyi Yang holds a PhD in Operations Management and an MBA, both from theUniversity of Chicago, Booth School of Business. He received dual bachelor'sdegrees in Industrial Engineering and English Language from TsinghuaUniversity.

Venue

信息管理与工程学院308室

上海财经大学（第三教学楼西侧）

上海市杨浦区武东路100号