We might like to think we're not influenced by other people, but a new study into the group-buying
mechanisms(机制) - like those used on coupon(优惠券) sites such as Groupon and LivingSocial-reveals
that telling buyers who come later to the offer how many have already signed up increases the number
of purchasers.
      Researchers at the University of Toronto's Rotman School of Management wanted to understand
why group buying sites that have entered the market recently have enjoyed greater success than those
operating a decade ago, such as Mercata and MobShop.
      Earlier attempts typically left potential buyers waiting for days before confirming whether or not they
had got the offer they had signed up for.
      "We think one of the reasons group-buying has been successful recently is because of the short tim
e horizon," says Rotman Professor Ming Hu, who co-wrote the study with Professor Mengze Shi and
PhD student Jiahua Wu. "It allows for a herding effect."
      Another reason is the use of an information structure that discloses to later arrivals how many have
already signed onto the deal.
      Researchers looked at two ways of designing the purchasing mechanism for a group buy: a
simultaneous mechanism, where no one knows how many buyers have come before them, and a
sequential(连续的) mechanism, where a second group of buyers has the advantage of knowing the
size of the first group.
      The researchers' analytical(分析的) model shows the most successful mechanism is the sequential
 one because it eliminates uncertainty for those coming later to the deal, and improves the confidence of
those who sign on early, as they're able to track the numbers of those who come after them.
      "That boosts confidence," says Professor Hu, who teaches operations management. Deals for
"luxury" services, versus everyday items, work better in a group buy scenario(方案) because they offer
consumers a greater benefit.