Consumers' decision to buy a product is based on its recommendation online: Study Penn State University researchers suggested that it's not just what is recommended, but how and why it's recommended, that helps to shape consumers' opinions. As more people go online for shopping, understanding how they rely on e-commerce recommendation systems to make purchases is increasingly important. Penn State University researchers suggested that it's not just what is recommended, but how and why it's recommended, that helps to shape consumers' opinions. Through the study published in the Journal of Advertising, the researchers investigated how people reacted to two product recommendation systems. The first system generated recommendations based on the user's earlier purchases -- often referred to as content-based recommendation systems.