Master's Thesis from the year 2013 in the subject Business economics - Offline Marketing and Online Marketing, grade: 1,3, ESCP Europe, course: Complexity, Ecommerce, Electronic Commerce, E-Satisfaction, Expertise Knowledge, Means-End Chain, Product Search Interfaces, Usability, Virtual Product Advisors, WebQual, Web Site Quality, Search Navigation, language: English, abstract: Consumers nowadays purchase a variety of products in online shops for different reasons. Certain products involve high involvement decision-making with low purchase frequencies in general. At the same time, virtual shelf space is unlimited and consumers face a variety of products, which exceeds their rational capabilities. This condition requires online shop operators to implement search tools in their web sites that allow consumers to structure and reduce complexity, both on a catalogue and a product level. Consumers in general do not always possess product expertise, especially in the case of low frequency purchases such as digital cameras. Virtual product advisors intend to fill this gap. The primary objective of the thesis is to investigate the interaction effect between different levels of consumer knowledge and a chosen product search approach. A special focus is put on a virtual product advisor and a facet search as a structuring tool. Based on theoretical work in marketing, psychology, information system management a set of hypotheses was developed pertaining to the interaction effect and how it affects the perceived quality of the online feature of a product search interface from a consumer perspective. A randomized experiment with a control group design in a live Online Shop was conducted to test the hypotheses. In sum, the findings suggest a contingency between the consumer knowledge and a product search interface in regard of the impact on antecedents of esatisfaction. The results provide two different angles from a marketing perspective in terms of usefulness and from an information system management point of view in terms of usability.