It's worth reading the actual paper closely. http://www.ccs.neu.edu/home/cbw/pdf/imc151-hannak.pdf http://www.ccs.neu.edu/home/cbw/pdf/imc151-hannak.pdf The a

It's worth reading the actual paper closely. http://www.ccs.neu.edu/home/cbw/pdf/imc151-hannak.pdf http://www.ccs.neu.edu/home/cbw/pdf/imc151-hannak.pdf The authors didn't find any smoking gun. None. Zero. They found some travel sites offering member discounts--no surprise there. They also found sellers were personalizing search rankings--no surprise again. And they found a persistent pricing differential for Home Depot, but were careful to note that it could be a server-side quirk.