It really is no surprise that having a great offer or promotion will effect sales. How good the offer is can really change the place a consumer is at in the Buyers Awareness Cycle moving them from consideration to purchase in a relatively short period of time. MediaPost states that "Online Retailers Have Opportunity To Influence Consumers" but I don't think that influence is exclusive to online retailers....
"The number of online shoppers who said they bought items not on their list when presented with an appealing offer or promotion rose since 2004, supporting the idea that consumers are more open to influence. An increase in impulse buying demonstrates that online buyers have become more comfortable with buying online, according to the study.
Only 33% of online shoppers had made their mind up in advance about the price they were willing to pay for the purchase. Even fewer began their research having made up their mind on all other purchase considerations, including the item or title to choose (31%), which store they would use (16%) or when to make their purchase (13%). With many of these considerations, shoppers had made fewer decisions than they had in 2004, indicating that the opportunity for influence has increased.
"This isn't a time to bury your head in the sand and go back to familiar strategies because more standard advertising isn't what consumers want or need to make purchase decisions," said Sam Decker, CMO at Bazaarvoice, Austin, Texas.
About 89% of consumers tend to rely on store and retail Web sites to find products, followed by 86% who rely on search engines, 78% who use manufacturer sites, and 77% who depend on ratings and reviews. Still, 42% of shoppers who plan to reduce spending visited three or more sites to research their most recent purchase. Many of them also relied on content discovery tools. "